SCHEDULE 14A

(RULE 14a-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION

PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE

SECURITIES EXCHANGE ACT OF 1934

(AMENDMENT NO.     )

Filed by the registrant ☒

Filed by a Party other than the registrant  ☐

Check the appropriate box:

Aon plc

(Name of Registrant as Specified in Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of filing fee (Check the appropriate box):

Notice of Annual General Meeting of Shareholders

We are pleased to invite you to join the board of directors (the “Board” or the “Board of Directors”) and senior leadership at the Aon plc (“Aon” or the “Company”) annual general meeting of shareholders (the “Annual Meeting”) scheduled for Friday, June 17, 2022 at 9:00 a.m. Irish Standard Time.

Items of Business:

Shareholders are strongly encouraged to vote their shares by proxy in advance of the Annual Meeting by one of the methods described on pages 68-69 of the proxy statement. Shareholders who wish to attend the Annual Meeting virtually may do so via webcast at www.meetnow.global/MCW6V7D, as further described on pages 70-71of the proxy statement. Note that attending the Annual Meeting virtually will not allow you to vote at the Annual Meeting. We intend to hold the Annual Meeting in person. However, we continue to monitor the COVID-19 pandemic; we are sensitive to the public health and travel concerns our shareholders may have and the protocols that various jurisdictions may impose. In the event we determine it is not possible or advisable to hold our Annual Meeting in person, we will announce alternative arrangements for the meeting as promptly as practicable, which may include holding the meeting by means of remote communication. We would publicly announce any such changes and how to participate in the meeting by press release and a filing with the Securities and Exchange Commission (“SEC”) as soon as practicable prior to the meeting. Any such determinations and changes will be made and communicated in accordance with SEC rules and requirements. Please monitor our Annual Meeting website at www.envisionreports.com/AON for updated information. If you are planning to attend our meeting, please check the website one week prior to the meeting date. During the Annual Meeting, the Board will present, for consideration by the shareholders, the Company’s statutory financial statements under Irish law for the fiscal year ended December 31, 2021 (including the reports of the directors and the Irish statutory auditor thereon) and a review of the Company’s affairs. We urge you to read the attached proxy statement for additional information concerning the matters to be considered at the Annual Meeting. The proxy statement shall be deemed incorporated into this notice.

Holders of Class A Ordinary Shares at the close of business on April 14, 2022 can vote at the Annual Meeting. A shareholder of record entitled to attend and vote at the Annual Meeting may appoint one or more proxies to attend, speak, and vote on his or her behalf by any of the procedures set out below and on pages 68-69 of the proxy statement. A proxy holder need not be a shareholder of record. To be valid, a proxy must be received by the Company using one of such procedures no later than 5:00 pm (Irish Standard Time) on June 16, 2022, the proxy deadline.

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting of Shareholders to be held on June 17, 2022

The proxy statement, our Annual Report for the fiscal year ended December 31, 2021 and our Irish financial statements are available at www.envisionreports.com/AON. This notice and proxy statement are first being mailed or made available to shareholders on or about April 29, 2022.

By Order of the Board of Directors,

Darren Zeidel

Company Secretary

April 29, 2022

Your vote is important

Only holders of Class A Ordinary Shares as of the record date April 14, 2022 can vote at the Annual Meeting. Please cast your vote as soon as possible in one of the following ways:

Proxy Summary

Voting Matters

Shareholders are being asked to vote on the following matters at the Annual Meeting:

2022 Aon Proxy Statement        1

Our Company and 2021 Highlights

The following is a summary of our 2021 performance across GAAP metrics, as well as the four non-GAAP metrics outlined above:

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The Aon Story: Our Colleagues, Culture and ESG

Culture

Our purpose is to shape decisions for the better – to protect and enrich the lives of people around the world. As colleagues, we are committed as one firm to our purpose, united through trust as one inclusive, diverse team, and passionate about making our colleagues and clients successful. We deliver for our colleagues by helping our colleagues achieve their full professional potential and we deliver for our clients by helping them protect and grow their businesses.

At Aon, we continue to relentlessly focus on building a sustainable culture of colleague wellbeing – that includes a focus on colleague physical health and safety, mental health and wellness, professional development and growth, and our smart working strategy. We stand by and support our colleagues as we continue to navigate and weather volatile circumstances in our world.

Inclusion and Diversity

Following the July 2021 termination of the proposed Willis Towers Watson combination, we announced the new Aon Executive Committee under the leadership of our CEO Greg Case. Forty-five percent of the members of our Aon Executive Committee leadership are female. The Inclusion and Diversity Sub-Committee of our Board of Directors met regularly with senior management throughout 2021 on Aon’s inclusion and diversity initiatives and progress across the regions in the areas of recruitment, education, representation, and promotion. We are committed to improving diversity at Aon at all levels of our organization and have published our workforce diversity data in our Annual Report on Form 10-K for the year ended December 31, 2021. Our 2021 EEO-1 Employer Information Report will be available on our website www.aon.com.

ESG and Risk

Management of environmental, social and governance (ESG) risks is an increasingly important priority for our clients. We partner with our clients in offering solutions designed to address and manage ESG issues for our clients. As a professional services firm, Aon’s management and oversight of social and human capital risk is a priority. The Board (or through its committees) regularly reviews and discusses people-related risks, including colleague satisfaction and engagement survey results, pay equity, colleague well-being, succession planning, employment law matters, and ethics hotline complaints. In 2020, the Board formed the Inclusion & Diversity Sub-Committee of the Governance/Nominating Committee to enhance the Board’s oversight of the Company’s inclusion and diversity strategies and initiatives. In 2021, Aon announced its commitment to achieve net-zero greenhouse gas emissions by 2030 in alignment with science-based targets.

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Board of Directors Composition

In February 2022, we announced that General Richard Myers will be retiring from our Board effective at the Annual Meeting. Upon General Myers’ retirement, our Board will be composed of 11 directors, 10 of whom are independent, including the Board Chair. It is a priority of the Governance/Nominating Committee to continue to identify candidates for the Board of Directors who have diverse backgrounds and bring fresh perspectives to the Board. In addition, the Governance/Nominating Committee advises the Board on refreshment of committee assignments and leadership. Beginning in June 2022, Jeff Campbell will serve as Chair of the Audit Committee and Cheryl Francis will serve as chair of the Inclusion & Diversity Sub-Committee. For more information on committee assignments and leadership taking effect in June 2022, please see pages 9-14.

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Directors

* Independent Director

** For information regarding committee memberships and chair assignments as of June 16, 2022, see pages 9 – 14.

^† Number of other public company boards

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Corporate Governance Highlights

Aon’s commitment to good corporate governance is integral to our business. Highlights of our strong corporate governance practices include:

2021 Executive Compensation Highlights

The core principle of our executive compensation program continues to be pay for performance, as we continue towards our goal of being the leading global professional services firm focused on risk, health, and wealth.

Leadership Performance Program. For each of our named executive officers (“NEOs”), the majority of his or her target compensation opportunity awarded in 2021 consisted of a long-term, performance-based grant under our Leadership Performance Program (“LPP”). In early 2022, we settled performance share units granted to our NEOs in 2019 under our fourteenth LPP cycle (“LPP 14”). The settlement of those units in Class A Ordinary Shares was contingent upon achieving adjusted diluted earnings per share of at least $25.98 (threshold performance) over the performance period from January 1, 2019 to December 31, 2021, and reflects achievement of adjusted diluted earnings per share of $30.98, which exceeded the stretch performance level adjusted diluted earnings per share of $29.71. Also in 2021, we granted performance share units under our sixteenth LPP cycle (“LPP 16”) to each of our NEOs, which are expected to be settled in 2024 contingent upon the Company’s adjusted diluted earnings per share performance over the January 1, 2021 to December 31, 2023 performance period.

Annual Incentive Compensation. Annual incentive bonuses paid to our NEOs reflected our application of the incentive pool funding guidelines adopted by the Organization and Compensation Committee (the “Compensation Committee”), as well as the committee’s evaluation of each NEO’s contributions to our business and financial results, delivery of key strategic initiatives, and personal leadership qualities. The incentive pool funding guidelines included both a comparison of current year adjusted operating income results against the prior year and a new People & Culture component for 2021, which assessed the Company’s progress on inclusion and diversity objectives. Target annual incentive opportunities for our NEOs for 2021, as a percentage of base salary, remained flat year over year. Once determined, annual incentives to our NEOs (other than Mr. Case) were paid 65% in the form of cash and 35% in the form of time-vested restricted share units in order to provide value to our executives that is tied to the long-term performance of the Company. Mr. Case’s annual incentive was paid 65% in the form of cash and 35% in the form of performance share units under our seventeenth LPP cycle, as a further tie to the long-term performance of the Company. Annual incentive bonuses for 2021 were paid to our NEOs in early 2022 following the Company’s achievement of adjusted operating income of $3,673 million.

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Compensation-Related Best Practices

Our compensation philosophy and related governance features are complemented by several policies and practices designed to align our executive compensation program with the long-term interests of our shareholders, including the following:

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Proposal 1–Resolutions Regarding the

Election of Directors

The Board of Directors unanimously recommends that shareholders vote “FOR” each nominee to serve as director.

What am I voting on?

The 11 current members of the Board named below are standing for election, in each case to serve until our 2023 annual general meeting.

The Governance/Nominating Committee of the Board (the “Governance/Nominating Committee”) has recommended to the Board that each director be nominated. With respect to Mr. Case, his employment agreement provides that he will be nominated for election as a director at each annual general meeting of shareholders during the period of his employment. All nominees for director have consented to being named in this proxy statement and have agreed to serve as directors if re-elected. We have no reason to believe that any of the nominees will not be available to serve as a director. However, if any nominee should become unavailable to serve for any reason, the proxies may be voted for such substitute nominees as may be designated by the Board or the Board may reduce its size.

The term of each director expires at the next annual general meeting of shareholders, and each director will continue in office until the election of his or her respective successor or until his or her earlier resignation or removal in accordance with the Company’s articles of association (the “Articles”) or the Irish Companies Act 2014, as amended (the “Irish Companies Act”). Consistent with the terms of the Articles, the Board currently is authorized to have up to 21 directors, and the number of directors was most recently set by the Board at 12. Richard B. Myers has decided to retire from the Board effective at the Annual Meeting. Following General Myers’ retirement, the Board expects to reduce the size of the Board to 11.

Each of the 11 nominees for director will be elected by the vote of a majority of the votes cast with respect to such nominee. A shareholder may: (i) vote for the election of a nominee; (ii) vote against the election of a nominee; or (iii) abstain from voting for a nominee. Unless an executed proxy contains instructions to the contrary, it is assumed that the proxy will be voted “FOR” the re-election of each nominee named on the following pages.

The form of shareholder resolution for this proposal is below:

RESOLVED THAT, the following individuals be, and each hereby is, by way of separate ordinary resolution, re-elected to serve as director until the election of his or her respective successor or until his or her earlier removal or resignation pursuant to the Articles:

Aon values a number of attributes and criteria when identifying nominees to serve as a director, including professional background, expertise, reputation for integrity, business, financial and management experience, leadership capabilities, and diversity. We believe all of the nominees are individuals with a reputation for integrity, demonstrate strong leadership capabilities, and are able to work collaboratively to make contributions to the Board and management.

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Director Nominee Bios

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Corporate Governance

We are committed to continually enhancing our corporate governance practices, which we believe help us sustain our success and build long-term value for our shareholders and other stakeholders. Aon’s Governance Guidelines provide the framework for our system of corporate governance, which, together with our committee charters and Code of Business Conduct, set forth standards of conduct for employees, officers and directors. The Board and its committees provide oversight of Aon’s overall performance, strategic direction, and executive management team performance, including management of the Company’s top risks and mitigation plans. The Board also reviews major initiatives and transactions and advises on key financial and business matters. The charter of each standing committee of the Board and the sub-committees of the standing committees, the Governance Guidelines, and the Code of Business Conduct are available on the corporate governance section of our website at http://www.aon.com/about-aon/corporate-governance/corporate-governance.jsp. For more information about our Board’s and management’s oversight of risk, including oversight of key environmental, social, and governance (“ESG”) risks, please see “Board Role in Risk Oversight” below.

Board Leadership Structure

The positions of Chief Executive Officer and Chair of the Board are held by separate individuals. Lester Knight has served as the Non-Executive Chair of the Board since 2008. The position of Non-Executive Chair is independent from management. As Non-Executive Chair, Mr. Knight sets the agendas for, and presides over, the Board meetings and also chairs executive sessions of the non-management directors. Our Chief Executive Officer is also a member of the Board and participates in its meetings. The Board believes the separation of the positions of Chief Executive Officer and Chair is the appropriate structure at this time as it allows our Chief Executive Officer to focus on the management of the Company and the Chair to ensure that the Board is focused on its oversight responsibilities, including independent oversight of management. The Board regularly assesses its leadership structure from time to time to ensure that the leadership structure is the most appropriate for the Company.

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Board Role in Risk Oversight

Risk is inherent and evolving in every business, and how well a business manages risk can ultimately determine its success. Our risk management program covers the range of material risks to Aon, including strategic, operational, financial, compliance, human capital, and social risks. The Board oversees Aon’s risk management program and allocates certain oversight responsibilities to its committees and sub-committees, as appropriate. Each committee regularly reports to the Board on risk matters under its purview. The Board and its committees periodically review our risk management policies, processes and controls (including enterprise risk management, or “ERM”).

Management carries out the daily processes, controls, and practices of our risk management program, many of which are embedded in our operations. In addition, as part of our ERM process, management identifies, assesses, prioritizes, and develops mitigation plans for Aon’s top risks. The Board believes that establishing the right tone at the top and maintaining full and open communication between management and the Board are essential for effective risk management and oversight. As such, the Board and the committees regularly analyze and discuss with management the Company’s risk landscape, ERM governance, and progress on key risk management priorities. Throughout the year, the Board and the committees review the Company’s management of risk, including but not limited to the areas of cyber security and data security, data privacy, business continuity, compliance with government regulations, financial performance, liquidity, taxes, mergers and acquisitions, and human capital management.

Cyber security, data security, and data privacy matters are an important focus of our Board’s oversight of risk. The Company’s management regularly presents (no less than twice annually) to the Audit Committee of the Board and/or the Compliance Sub-Committee of the Audit Committee regarding cyber security, data security, and data privacy matters. Our colleagues are required to complete trainings on at least an annual basis with respect to privacy and data protection. For more information on committee and sub-committee responsibilities with respect to risk oversight, please see the section titled “Board of Directors and Committees” below. In addition, members of senior management attend Board and committee meetings (including private sessions with independent directors when invited) and are available to address any questions or concerns raised by the Board related to risk management and any other matters.

Our Board and management recognize that the full spectrum of ESG risks are evolving in their significance to the business, and accordingly, oversight of ESG risks is a continuing and dynamic commitment. The Board (or through its committees) regularly reviews the Company’s top ESG risks, including human capital management, where the full Board, the Inclusion & Diversity Sub-Committee, the Compensation Committee and the Compliance Sub-Committee oversee the Company’s management of people-related risks. For more information on Aon’s ESG efforts, please see our latest Aon Impact Report, which can be found on the Company’s website, www.aon.com. The information in the Aon Impact Report is not incorporated by reference into, and does not form part of, this proxy statement.

Director Independence

Aon’s Governance Guidelines require that a majority of directors meet the categorical independence standards adopted by the Board, which will meet or exceed the independence requirements of the New York Stock Exchange (“NYSE”). The Governance Guidelines further provide that each of the Audit Committee, Governance/Nominating Committee and Compensation Committee be composed entirely of independent directors.

The Board has affirmatively determined that each nominee for director other than Mr. Case is independent under the categorical standards adopted by the Board, applicable legal requirements, and the rules of the NYSE. Mr. Case is considered a management director because of his position as our Chief Executive Officer. In addition, the Board has affirmatively determined that General Myers, who will retire from the Board effective as of the Annual Meeting, is independent under the categorical standards adopted by the Board, applicable legal requirements, and the rules of the NYSE.

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In determining that each of the non-management directors is independent, the Board also considered the following relationships that it deemed were immaterial to such director’s independence:

Board of Directors and Committees

The Board met eight times in 2021 during 2021. All nominees for director who served as a director in 2021 attended at least 75% of the total meetings of the Board and the standing committees and sub-committees on which they served.

In accordance with NYSE rules and the Governance Guidelines, non-management directors meet regularly in executive session without management. Mr. Knight chairs these executive sessions.

The Board has five standing committees: the Executive Committee, the Audit Committee, the Finance Committee, the Governance/Nominating Committee and the Compensation Committee. The Board has also established the Compliance Sub-Committee as a standing sub-committee of the Audit Committee and the Inclusion & Diversity Sub-Committee as a standing sub-committee of the Governance/Nominating Committee.

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Other Corporate Governance Practices

Board and Committee Evaluations

Our Board engages in ongoing self-evaluation and assessment. Annually, the directors review and complete evaluations on Board effectiveness, committee performance and peer assessment. The Board retains an outside party to review the completed evaluations. Each of the committees and the full Board discuss their self-assessments in executive sessions at least annually. The Governance/Nominating Committee periodically reviews the form and process for Board and Committee self-evaluations.

CEO Succession Planning

Our Independent Board Chair oversees the Chief Executive Officer succession planning process. The Board, at least annually, discusses CEO succession planning, including emergency succession plans and process. The Board also regularly reviews and discusses senior leadership succession planning and development.

Director Selection and Shareholder Recommendations

Consistent with the Governance Guidelines, the Governance/Nominating Committee seeks members from diverse backgrounds who combine a broad spectrum of experience and expertise with a reputation for integrity. The Governance/Nominating Committee also considers whether a potential nominee would satisfy independence standards adopted by the Board and the requirements of the NYSE.

The Board values diversity as a factor in selecting nominees to serve on the Board. In selecting nominees for director, the Governance/Nominating Committee considers professional background, reputation for integrity, leadership capabilities, skills and experience in the context of the needs of the Board, diversity, including gender and racial/ethnic diversity, and international experience and perspectives. Of the 11 director nominees for election at the Annual Meeting, 2 directors are Asian, 1 director is Black and 1 director is Hispanic; 3 of the 11 director nominees are women. For more information regarding director diversity and the racial/ethnic demographics of each of our directors, see page 4 of this proxy statement. Although there is no specific policy with regard to the consideration of diversity in identifying director nominees, the Governance/Nominating Committee considers, and requests that the search firms it engages include, women and racially/ethnically diverse persons in potential director candidates for consideration by such Committee.

When a vacancy exists on the Board due to the expansion of the size of the Board or the resignation or retirement of an existing director, the Governance/Nominating Committee identifies and evaluates potential director nominees. The Governance/Nominating Committee has sole authority to retain and terminate any search firm to be used to identify director candidates and sole authority to approve such search firm’s fees and other retention terms. The Governance/Nominating Committee recommends potential director candidates to the full Board, which is responsible for final approval of any director candidate. This process is the same for director candidates who are recommended by our shareholders. The effectiveness of the nomination process, including the criteria used for selecting nominees for director, is evaluated by the Board each year as part of its annual self-evaluation process and by the Governance/Nominating Committee as it evaluates and identifies director candidates.

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The Governance/Nominating Committee will consider shareholder recommendations for director candidates. Recommendations, together with the name and address of the shareholder making the recommendation, relevant biographical information regarding the proposed candidate and a description of any arrangement or understanding between the shareholder and the proposed nominee, should be sent to the Company Secretary. Recommendations for director candidates to stand for election at the 2023 annual general meeting must be submitted in writing to the Company Secretary, Aon plc, Metropolitan Building, James Joyce Street, Dublin 1, Ireland. Recommendations will be forwarded to the Chair of the Governance/Nominating Committee for review and consideration. For information regarding the requirements applicable to nominations, see “Shareholder Proposals for 2023 Annual General Meeting” on page 66 of this proxy statement.

Communications with the Board of Directors

Shareholders and other interested parties may communicate with the Board, our independent Chair, or any of our directors by contacting the non-management directors of Aon plc, c/o the Company Secretary, Metropolitan Building, James Joyce Street, Dublin 1, Ireland. Alternatively, shareholders and other interested parties may communicate with Aon’s non-management directors or any of our directors via electronic mail to the following address: corporate.governance@aon.com.

The non-management directors have established procedures for handling communications from shareholders and other interested parties. Communications are distributed to the Chair of the Governance/Nominating Committee, the full Board, the non-management directors, or to any individual director or directors as appropriate, depending on the facts and circumstances outlined in the communication. Solicitations, spam, junk mail and mass mailings, resumes and other forms of job inquiries, business solicitations or advertisements and frivolous or inappropriate communications will not be forwarded, but will be made available to any non-management director upon request.

Shareholder Engagement

In 2021, we continued our focus on regularly engaging with our shareholders. During these meetings, we discussed many topics, including our corporate governance structure, our results and strategy and our corporate responsibility. We continued our conversations with our investors about our Board’s oversight of risks, including the impacts of the terminated Willis Towers Watson combination and the ongoing impacts of the COVID-19 pandemic on our business, our employees, and the broader economy. Investors were generally supportive of many of the Company’s practices and highlighted the importance of engaging with them in the future on long-term corporate strategy and corporate social responsibility initiatives. These discussions provide valuable insights into our shareholders’ views. We plan to continue to actively engage with our shareholders to better understand and consider their views.

Majority Voting

The Articles require that directors be elected by majority vote in uncontested elections. In a contested election, directors will be elected by plurality vote. In addition, the Governance Guidelines provide that any incumbent director who fails to receive an affirmative majority of the votes cast, in person or by proxy, by shareholders entitled to vote at the Annual Meeting in an uncontested election (and who is not otherwise removed by ordinary resolution of the shareholders) must immediately offer to tender his or her resignation to the Board. The Board will then determine, through a process overseen by the Governance/Nominating Committee, whether to accept the resignation, reject the resignation, or take other action. The Board will act on the recommendation of the Governance/Nominating Committee.

Share Ownership Guidelines

The Board has adopted Share Ownership Guidelines for Non-Management Directors and Officer Share Ownership Guidelines. The Share Ownership Guidelines for Non-Management Directors require each non-management director to hold an investment position in Class A Ordinary Shares equal to five times the annual director retainer and provide a transition period of five years for non-management directors to achieve the requisite ownership level; provided, however, that each new non-management director is expected to hold 1,000 Class A Ordinary Shares within the first year of joining the Board. The guidelines serve to increase our non-management directors’ equity stakes in Aon and align Aon’s non-management directors’ interests more closely with those of Aon’s shareholders. Compliance with the Share Ownership Guidelines for Non-Management Directors is measured on the first trading day of each calendar year, and each non-management director was in compliance for 2021. Further information on the Officer Share Ownership Guidelines for Aon’s senior executives can be found in the section captioned “Compensation Discussion and Analysis.”

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Hedging and Pledging Shares

The Board has adopted a policy prohibiting all directors and employees from engaging in short sales, publicly traded options, puts and calls, forward sale contracts, and other swap, hedging and derivative transactions relating to our securities. The Board also has adopted a policy prohibiting our executive officers and directors from holding our securities in margin accounts or pledging our securities as collateral for a loan.

Clawback Policy and Forfeiture Provisions

The Board has adopted an incentive repayment policy (the “Clawback Policy”) applicable to Aon’s executive officers. Pursuant to the Clawback Policy, the Board may cancel or require reimbursement of any incentive payments or equity-based awards received if the incentive payment or equity award was based on the achievement of financial results that are subsequently restated. If the Board determines that the executive officer engaged in fraud that caused or partially caused the need for the financial restatement, the incentive payment or equity-based award is required to be forfeited or reimbursed in full. If the restatement was not the result of fraud by the executive officer, the Board may, to the extent allowed under applicable law, require forfeiture or reimbursement of the amount the incentive payment or equity-based award exceeded the lower amount that would have been made based on the restated financial results. In addition, beginning with equity-based awards granted in 2019, unvested equity-based awards are subject to forfeiture in the event of a material violation of the Company’s policies or procedures or a breach of applicable restrictive covenants.

Attendance at Annual General Meeting

The Governance Guidelines provide that directors are expected to attend the annual general meeting. All of our then-serving Board members attended our 2021 annual general meeting virtually or in person.

Certain Relationships and Related Transactions

Aon has adopted a Related Person Transaction Policy governing the review and approval of related party transactions. The terms of these procedures provide that the Governance/Nominating Committee will review transactions in which: (i) Aon is a party or participant; and (ii) any director, executive officer, or holder of five percent (5%) or more of Aon’s voting securities, an immediate family member of any such person or an entity controlled by any such person or immediate family member, has a direct or indirect material interest. To facilitate the review and approval of related party transactions, Aon’s directors and executive officers complete an annual director and officer questionnaire and disclose all potential related person transactions involving themselves and their immediate family members. Throughout the year, directors and executive officers are required to notify Aon’s General Counsel of any potential related person transactions of which they become aware. Aon’s General Counsel reports these transactions, as well as any other related party transactions of which he is aware, to the Governance/Nominating Committee. The Governance/Nominating Committee considers all relevant facts of any related party transactions to determine whether to approve or ratify the transaction. There have been no related person transactions or pending related person transactions since January 1, 2021 that require disclosure pursuant to Item 404 of Regulation S-K.

Delinquent Section 16(a) Reports

Section 16(a) of the Exchange Act requires that each of our directors and executive officers, and any other person who owns more than ten percent (10%) of our Class A Ordinary Shares, file with the SEC initial reports of ownership and reports of changes in ownership of our Class A Ordinary Shares. To our knowledge, based solely on information furnished to us and written representations by such persons that no such other reports were required to be filed, Aon believes that all such SEC filing requirements were met in a timely manner during 2021 other than with respect to a Form 4 filed on behalf of Mr. Knight to report the purchase of shares on August 4, 2021, which was reported one day late.

Compensation Committee Interlocks and Insider Participation

During 2021, the Compensation Committee was composed of Mr. Notebaert (Chair), Mr. Cai, Mr. Campbell, Ms. Francis, General Myers and Dr. Woo. No member of the Compensation Committee was, during 2021 or previously, an officer or employee of Aon or any of its subsidiaries. In addition, during 2021, there were no Compensation Committee interlocks required to be disclosed.

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Security Ownership of Directors and

Executive Officers

The following table sets forth the number of Class A Ordinary Shares beneficially owned as of April 14, 2022 by each of Aon’s directors and NEOs and by Aon’s directors, nominees and executive officers as a group. As used in this proxy statement, “beneficially owned” means a person has, or may have within 60 days, the sole or shared power to vote or direct the voting of a security and/or the sole or shared investment power with respect to a security (i.e., the power to dispose or direct the disposition of a security). No shares held by Aon’s directors or executive officers are pledged as security. The address of each person named in the table below is c/o Aon plc, Metropolitan Building, James Joyce Street, Dublin 1, Ireland.

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Principal Holders of Voting Securities

As of April 14, 2022, the beneficial owners of 5% or more of Aon’s Class A Ordinary Shares entitled to vote at the Annual Meeting and known to the Company were:

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Proposal 2–Advisory Resolution on Executive Compensation

The Board unanimously recommends that shareholders vote “FOR” advisory approval of the compensation of Aon’s NEOs.

What am I voting on?

In accordance with applicable law and Section 14A of the Exchange Act, we are providing shareholders with the opportunity to vote on an advisory resolution, commonly known as “say on pay,” approving Aon’s executive compensation as reported in this proxy statement. At our 2021 annual general meeting, we provided shareholders with the opportunity to vote on an advisory resolution regarding the executive compensation of our NEOs as disclosed in the proxy statement for the 2021 annual general meeting, and shareholders approved the proposal by a large majority. We currently conduct advisory “say-on-pay” votes on an annual basis, and we expect to conduct our next advisory vote at our 2023 annual general meeting of shareholders.

We encourage shareholders to read the Compensation Discussion and Analysis beginning on page 25 of this proxy statement, which describes in detail how our compensation policies and procedures operate and are designed to achieve our compensation objectives of (1) directly linking the compensation of our NEOs to our performance and (2) aligning the financial interests of our NEOs with those of our shareholders. We further encourage our shareholders to refer to the Summary Compensation Table for Fiscal Years 2021, 2020 and 2019, and other related tabular and narrative disclosures beginning on page 40 of this proxy statement, which provide detailed information on the compensation of our NEOs.

The Board and the Compensation Committee believe that the policies and procedures articulated in the Compensation Discussion and Analysis are effective in achieving our compensation objectives and that the design of our compensation program and the compensation awarded to our NEOs fulfill these objectives.

The form of shareholder resolution for this proposal is below.

RESOLVED THAT, the shareholders approve, on an advisory basis, the compensation of the Company’s named executive officers as described in the proxy statement for the 2022 Annual General Meeting of the Company under “Compensation Discussion and Analysis” and “Executive Compensation,” including the tabular and narrative disclosure contained in the proxy statement.

Is this vote binding on the Board?

As this vote is advisory, it will not be binding upon the Board or the Compensation Committee, and neither the Board nor the Compensation Committee will be required to take any action (or refrain from taking any action) as a result of the outcome of the vote on this proposal. The Compensation Committee will review and consider the outcome of the vote in connection with the ongoing review of Aon’s executive compensation programs.

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Compensation Discussion and Analysis

This Compensation Discussion and Analysis (“CD&A”) describes our executive compensation program for our NEOs, who are listed below, for 2021. We recommend that you read this section in conjunction with the executive compensation tables and corresponding footnotes that follow, as it provides context for the amounts shown in the tables and the footnote disclosures.

Executive Summary

Who We Are

Aon exists to shape decisions for the better — to protect and enrich the lives of people around the world. Our colleagues provide our clients in over 120 countries with advice and solutions that give them the clarity and confidence to make better decisions to protect and grow their business.

2021 Business Highlights

In assessing our performance, we focus on our performance against four non-GAAP metrics that we communicate to shareholders: organic revenue growth, adjusted operating margin, adjusted diluted earnings per share, and free cash flow. These non-GAAP metrics should be viewed in addition to, not instead of, our consolidated financial statements and notes thereto. A reconciliation of these non-GAAP metrics to the most directly comparable GAAP metrics is set forth in Appendix A to this proxy statement.

In 2021, we continued to deliver across these four metrics:

Performing at the levels described above allows us to continue to execute on our goals of strategically investing in long-term growth, improving return on invested capital, and effectively allocating capital.

During 2021, we returned nearly $4.0 billion of capital to our shareholders, including over $3.5 billion in share repurchases and $447 million in dividends, which highlights our strong cash flow generation and effective allocation of capital. During Mr. Case’s leadership, which began in April 2005, our average annual total shareholder return has been 18%, compared to the return of the benchmark S&P 500 of 9% and 12% for our direct peer averages (Arthur J. Gallagher & Co., Brown & Brown, Inc., Marsh & McLennan Companies, Inc., and Willis Towers Watson Public Limited Company). We believe we are well positioned to create long-term value by improving our growth profile and operating performance and generating strong free cash flow.

We compensate our senior executives through incentive programs that measure both long-term and short-term performance. Our long-term incentive program (described in this CD&A under “Leadership Performance Program Under Our Shareholder-Approved

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Plan”) is based on adjusted cumulative diluted earnings per share, a measure driven by operational performance and capital management, across overlapping three-year performance periods. Our short-term incentive program (described in this CD&A under “Annual Incentive Awards Under Our Shareholder-Approved Plan”) is primarily based on adjusted operating income, a measure driven by operating margin and organic revenue growth, as well as a people and culture component, which assesses the Company’s progress against inclusion & diversity objectives.

We achieved strong results across these metrics, which were the key performance measures under our 2021 annual and 2019-2021 long-term incentive compensation programs. Set forth below are the results across these metrics as well as the results against their GAAP comparative metrics:

In addition, the Company has achieved progress against our quantitative inclusion & diversity objectives, including eliminating promotion rate gaps across the talent pipeline for women globally and for colleagues of racially/ethnically diverse backgrounds in the United States. Similarly strong progress was made in the education strategy pillar as colleagues’ views of the firm’s advocacy for diversity, equity, and inclusion exceeded the pre-established quantitative goal and perception gaps amongst cohorts were reduced. The Company’s progress across quantitative goals within its inclusion & diversity initiatives accounts for 20% of the performance metric used to determine funding under the annual incentive plan.

Because our short-range or long-range corporate planning may dictate a change to the metrics we use over time, we expect to continue reassessing the metrics that we use in our compensation programs annually.

Features of Our Executive Compensation Program

The following table provides an overview of our compensation program elements for our NEOs. The guiding philosophy underlying our executive compensation program is to provide a fair, flexible, and market-based total compensation package that is meaningfully tied to the Company’s short- and long-term performance and aligned with the interests of our shareholders.

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Our Pay for Performance Orientation and Executive Compensation Philosophy

The core principle of our executive compensation program continues to be pay for performance, as we continue towards our goal of being the leading global professional services firm focused on risk, health, and wealth. That core principle dictates that performance-based pay elements (which constitute the bulk of our NEOs’ total direct compensation (consisting of base salary, actual cash annual incentive compensation paid for 2021 performance, and long-term incentive compensation granted in 2021, with long-term equity awards valued based on grant date value assuming target performance)) will not be earned or paid unless specified performance objectives are achieved. For 2021, performance-based compensation comprised approximately 92% of the total direct compensation for Mr. Case and averaged approximately 86% of the total direct compensation for our other NEOs:

The “performance-based” pay component shown in the above graphs is the sum of (1) the cash portion of the NEO’s bonus paid for 2021 performance, plus (2) the target value of all equity awards granted to the NEO during 2021. The “fixed” pay component is the NEO’s 2021 base salary. For our NEOs other than Mr. Case, the actual performance-based percentage of total direct compensation ranged from 74% to 91%. Please refer to the Summary Compensation Table below for complete disclosure of the total compensation paid to our NEOs serving in that capacity during the prior three years.

In addition to our focus on pay-for-performance, our executive compensation program is complemented by several practices designed to mitigate compensation-related risk and align with the long-term interests of our shareholders:

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The Executive Compensation Process

Process of Determining Executive Compensation

Management assists the Compensation Committee in developing and administering our executive compensation programs. Direct responsibilities of management include, but are not limited to:

In the first quarter of 2021, our independent directors evaluated our Chief Executive Officer’s performance and compensation. At that time, the Compensation Committee also evaluated the performance and reviewed the compensation of our other executive officers. During this review, the Compensation Committee approved for each executive officer a target annual incentive for 2021 performance and the specific corporate performance metrics that our performance would be measured against for purposes of this incentive award. The Compensation Committee also approved in March 2021 a target number of performance share units to be awarded to each executive officer under the LPP. Additionally, the Compensation Committee granted a supplemental award of performance share units under LPP to each of Ms. Davies and Mr. Andersen in August 2021 following the termination of the proposed combination with Willis Towers Watson, as discussed in more detail in the section “Long-Term Leadership Performance Program under Our Shareholder-Approved Plan.”

In early 2022, in connection with the Compensation Committee’s annual compensation review, management presented the Compensation Committee with compensation tally sheets reporting compensation paid for the prior four years and the best-available competitive pay data. The Compensation Committee also reviewed and considered Aon’s overall performance

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against targets that were established for 2021. This review culminated in certain compensation decisions made by the Compensation Committee with respect to our executive officers during the first quarter of 2022, which are described in more detail below.

Engagement of Compensation Consultant

The Compensation Committee directly engages and regularly consults with its independent compensation consultant about ongoing executive compensation matters. In June of 2021, the Compensation Committee engaged Meridian Compensation Partners, LLC (“Meridian”) to serve as its independent compensation consultant, replacing Frederic W. Cook & Co., Inc. (“FW Cook”), who served as its independent compensation consultant prior to Meridian’s engagement. For purposes of this Compensation Discussion and Analysis, Meridian and FW Cook are collectively referred to as the “Compensation Consultant.”

The Compensation Consultant provides expertise and advice on various matters coming before the Compensation Committee. The Compensation Consultant is engaged by, and reports directly to, the Compensation Committee, and does not advise management or receive other compensation from Aon. The Compensation Consultant typically participates in all Compensation Committee meetings and communicates with the Chair of the Compensation Committee between meetings. During 2021, The Compensation Consultant assisted the Compensation Committee by: advising on our compensation philosophy, objectives, and strategy; developing criteria for identification of our peer group for executive and Board compensation and Company performance review purposes; reviewing management’s design proposals for short-term cash and long-term equity incentive compensation programs; assessing risks arising from our compensation policies and practices; providing change in control severance calculations for our NEOs in the 2021 annual proxy disclosure; providing compensation data from our peer group proxy and other disclosures; advising and providing comments on management’s recommendations regarding executive officers’ annual incentives for 2021 and equity-based awards granted in 2021; reporting on executive-compensation related trends and regulatory initiatives; reporting on the impact of the COVID-19 pandemic on executive compensation and director pay programs at peer group companies; and advising on potential alternatives for Aon’s executive and director compensation programs. Management periodically retains other consulting firms to provide pay survey data and other non-executive compensation services that may be presented to or reviewed by the Compensation Committee.

The Compensation Committee has assessed the independence of Meridian and its predecessor FW Cook pursuant to SEC and NYSE rules and concluded that no conflict of interest exists that would prevent Meridian or FW Cook from serving as an independent consultant to the Compensation Committee.

How We Determine Compensation

The Compensation Committee generally targets a competitive level and mix of total direct compensation elements using market data as a reference point. For 2021, the Compensation Committee did not use a specific formula or comparative percentile targets to determine total compensation, individual components of compensation, or the relative mix of pay components, and the establishment of compensation levels in 2021 was not a mechanical process. Rather, the Compensation Committee used its judgment and business experience. The Compensation Committee’s overall intent was to evaluate the various elements of total compensation so that the emphasis of the Company’s compensation program was on its variable components of pay in the form of long-term equity awards and annual bonus awards, and the amounts earned under such programs, which fluctuates based on Aon’s performance.

Use of Tally Sheets

The Compensation Committee regularly reviews compensation tally sheets. The tally sheets assign dollar amounts to each component of the executive’s compensation, including base salary, annual incentives (target and actual), long-term incentives granted and outstanding, employee benefits (including health care and qualified and nonqualified retirement plans), relocation benefits, including income tax equalization, perquisites, and potential change in control severance payments. The tally sheets are presented to the Compensation Committee to help ensure that it is aware of all rewards components and the value of such components when making compensation decisions.

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Involvement of Mr. Case in the Compensation Process

Each year, the Compensation Committee approves all elements of compensation for our NEOs and other executive officers (other than Mr. Case). These decisions are typically made during the annual compensation review process conducted in the first quarter of the year. The Compensation Committee solicits certain recommendations from Mr. Case and our Chief People Officer.

Mr. Case recommends to the Compensation Committee the equity award, annual incentive payment, and base salary adjustments, if any, for the executive officers who report directly to him. He has direct knowledge of the contributions made to Aon by these executive officers, and he shares this knowledge with the Compensation Committee and provides feedback on the performance of his direct reports.

During the annual review process, our Chief People Officer and the Chair of the Compensation Committee work together on Mr. Case’s annual evaluation report, which summarizes Mr. Case’s qualitative and quantitative performance for the year. The report is considered, along with other factors (including the Compensation Committee’s own assessment of Mr. Case’s performance, relevant market data, and Aon’s overall performance), in recommending Mr. Case’s compensation to the independent directors of the Board.

The Compensation Committee has the ultimate authority to make compensation decisions for our NEOs and other executive officers except for Mr. Case, whose compensation is approved by the independent directors of the Board. The Compensation Committee discusses its preliminary compensation decisions with the independent members of the Board who do not serve on the Compensation Committee. As part of this process, these directors share their evaluations of the executives’ performance. The sharing of performance review information also aids the directors in carrying out their succession planning responsibilities. After considering input from those directors, the Compensation Committee makes its final determinations.

Mr. Case, together with our Chief People Officer and our Chief Financial Officer, makes recommendations to the Compensation Committee relating to the performance targets to be established under Aon’s annual incentive and long-term equity incentive programs. The Compensation Committee reviews such recommendations with its Compensation Consultant and reserves the ultimate authority to set such targets and to determine whether such goals were achieved.

Result of Advisory Vote by Shareholders on Our “Say on Pay” Proposal

The Compensation Committee considered the results of the advisory vote by shareholders on the “say on pay” proposal presented to our shareholders at our 2021 annual general meeting of shareholders. As reported in our Current Report on Form 8-K, filed with the SEC on June 4, 2021, approximately 92% of shareholder votes cast at that meeting were voted in support of the compensation program offered to our NEOs for 2020. Accordingly, the Compensation Committee made no changes to our executive compensation programs in response to this vote.

Internal Pay Relationships

In determining an executive officer’s target annual incentive or long-term performance award value, the Compensation Committee will, from time to time, consider internal pay relationships. However, the Compensation Committee has not adopted a broad internal pay equity policy pursuant to which each executive officer’s compensation, or one or more components thereof, is related to or benchmarked against the compensation of other executive officers.

Analysis of Key 2021 Compensation Decisions

Peer Group

The Compensation Committee selects our executive compensation peer group based on a process that considers objective criteria including: industry segment; revenues, market capitalization, assets, and employee headcount; business complexity; and global footprint, as well as peers of our direct peers (“peers of peers”) and proxy-advisor peer groups. The Compensation Committee’s goal is to have relevant market data to inform its decisions on pay levels and practices. As such, the Compensation Committee looks for a peer group that is balanced with larger and smaller companies in a comparable range, and to have continuity through an annual review process.

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The defined criteria used to establish our peer group include global financial services industry companies or major professional services firms with which we compete for executive talent and/or financial capital that are between one-fourth and four times our size in average market capitalization (calculated over the most recent eight quarters to reduce volatility), between one-fourth and four times our size in trailing four-quarter revenues, and that have latest year total assets less than $500 billion.

In 2020, we reviewed our peer group with the Compensation Consultant and concluded that DXC Technology Solutions Corporation should be removed as it no longer meets our defined criteria, and Automatic Data Processing should be added in its place, to form our 2021 peer group. The Compensation Committee referred to the 2021 peer group when determining the compensation, including actual annual incentive awards paid in 2022 related to 2021 performance. In 2021, we reviewed our peer group with the Compensation Consultant and concluded that no changes should be made to the peer group for 2022. Our 2021 and 2022 peer group members are listed below.

Base Salary

Using the peer group and executive compensation review processes outlined above, the Compensation Committee annually considers and reviews salaries for our executive officers. Base salaries are adjusted periodically to, among other things, recognize changes in job responsibilities or bring the fixed component of an executive’s total compensation in line with his or her peers at the Company or the industry generally. Base salary adjustments generally take effect on April 1.

As Ms. Stevens and Mr. Zeidel were promoted to their respective roles in 2019, development and further growth in their roles were reviewed by the Committee in 2021 and 2022. As a result of the review, the base salary for Ms. Stevens was adjusted from $700,000 to $900,000, and the base salary for Mr. Zeidel was adjusted from $600,000 to $750,000, each effective as of April 1, 2021. In early 2022, the Committee again reviewed the performance and growth of the NEOs in both capability and scope against the competitive market for top talent and adjusted the base salaries for four of our NEOs were adjusted, each effective as of April 1, 2022: the base salary for each of Ms. Davies and Mr. Andersen, was adjusted from $1,000,000 to $1,250,000; Ms. Stevens, whose base salary was adjusted from $900,000 to $1,000,000; and Mr. Zeidel, whose base salary was adjusted from $750,000 to $900,000. These adjustments took into account market positioning in an intensely competitive environment, business and financial results, individual delivery of key strategic initiatives, leadership capabilities, advancement potential, and internal equitability.

Long-Term Leadership Performance Program under Our Shareholder-Approved Plan

The LPP is a sub-plan of our Shareholder-Approved Plan, which means that LPP awards are subject to terms approved by our shareholders. Each award granted under the LPP consists of performance share units that are eligible to vest over a three-year period based on achievement of adjusted cumulative diluted earnings per share targets over that period. The Compensation Committee historically has approved LPP awards for our NEOs each year. The three-year LPP performance cycles run concurrently, so we may have up to three active cycles during a given year. For example, during 2021, our NEOs held LPP 14, LPP 15, and LPP 16 awards (for the 2019-2021, 2020-2022, and 2021-2023 performance periods, respectively). This design is intended to ensure that our NEOs remain focused on long-term sustainable performance while providing the Compensation Committee with the ability to evaluate performance metrics on a regular basis. We do not pay dividends or dividend equivalents on performance share units.

During the first quarter of 2021, we granted performance share units to our executive officers, including each NEO, pursuant to LPP 16 (2021-2023 performance period). Additionally, as discussed further below, we granted a supplemental award of

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performance share units pursuant to LPP 16 to each of Ms. Davies and Mr. Andersen in August 2021. During the first quarter of 2021, we determined our actual levels of achievement under LPP 14 (2019-2021 performance period).

LPP 16 (2021 Grant for 2021-2023 Performance Period). This is our sixteenth annual three-year performance cycle for long-term incentive awards granted to our most senior leaders. The LPP is intended to further strengthen the relationship between wealth accumulation for our executives and long-term financial performance of the Company and increase in shareholder value. The performance share units awarded under LPP 16 are payable (to the extent earned) in the form of Class A Ordinary Shares. The grant date value of the awards (at target) was determined and approved by the Compensation Committee. From that value, the number of target performance share units was calculated on the date of grant based on that day’s closing price for Class A Ordinary Shares on the NYSE. The performance share units under LPP 16 will be earned and settled in a range of 0% (if the threshold level of performance is not achieved) to 200% of the target number of shares (if the maximum level of performance is achieved) based on the Company’s cumulative adjusted diluted earnings per share over the three-year performance period.

The performance results for LPP 16 will be measured against the three-year publicly reported cumulative adjusted diluted earnings per share target rate, subject to limited adjustments set forth in the program documentation at the beginning of the three-year period. The adjustments are intended to exclude the impact of unusual or infrequently occurring items, to provide a target that, while challenging, eliminates the impact of certain events and circumstances outside of the control of the relevant executive officers. The Compensation Committee’s selection under LPP 16 of the three-year performance period and cumulative adjusted diluted earnings per share financial performance metric is intended to provide the award recipients a reasonable period within which to achieve and sustain what are intended to be challenging long-term growth objectives. The Compensation Committee believes adjusted diluted earnings per share is a more effective measure of Company performance for purposes of motivating executive performance than against earnings per share calculated in accordance with U.S. GAAP, as the adjusted measure provides a target that is within the executives’ control and area of accountability. Further, the Company believes that adjusted diluted earnings per share provides a perspective on the Company’s ongoing core operating performance that is consistent with how shareholders measure our success and that creates transparency and clarity for participants.

In determining the individual awards under LPP 16 granted in the first quarter of 2021, the Compensation Committee considered internal pay relationships, the award recipient’s compensation mix, and total direct compensation, including the recipient’s total direct compensation for 2020 relative to similarly-situated executives at our 2021 peer group members. Additionally, we granted a supplemental award of performance share units pursuant to LPP 16 to each of Ms. Davies and Mr. Andersen in August 2021 following the termination of the proposed combination with Willis Towers Watson. These awards were made to recognize their exceptional performance in managing the integration while delivering record growth, to promote their continued retention in a competitive market for senior leaders of their caliber and expertise, and to strengthen the stability of the leadership of the firm going-forward. For further information regarding individual awards under LPP 16, see footnote (1) in the Summary Compensation Table below, and also the Grants of Plan-Based Awards in Fiscal Year 2021 below.

LPP 14 (2019 Grant for 2019-2021 Performance Period). In early 2022, we determined the actual achievement under LPP 14. The performance period for LPP 14 ended on December 31, 2021.

LPP 14—Performance Share Units (Performance Period 1/1/2019—12/31/2021)

For LPP 14, the cumulative adjusted diluted earnings per share goals from continuing operations ranged from a threshold level of $25.98, below which no payout would occur, to $29.71 or higher, which would yield shares equal to 200% of the target number. A result of $27.01 in cumulative adjusted diluted earnings per share from continuing operations would have yielded shares equal to 100% of the target number. This target performance represented a 25.8% increase over the EPS

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target for the thirteenth cycle of our LPP established for the performance period from 2018 through 2020 (“LPP 13”). Our actual cumulative adjusted diluted earnings per share from continuing operations for the three-year period of 2019-2021 was $30.98, resulting in a payout at 200% of the target number of shares awarded.

Annual Incentive Awards under Our Shareholder-Approved Plan

Annual Incentives. Under our Shareholder-Approved Plan, the Compensation Committee annually approves the framework for our annual incentive compensation plan, including the applicable Aon-wide performance metric and minimum achievement threshold against that performance metric. If the threshold level performance metric is not met, no annual bonuses are payable under our Shareholder-Approved Plan. If the minimum achievement threshold is achieved, our Shareholder-Approved Plan allows for the payment of current-year annual incentives to our executive officers up to a cap of the lesser of $10 million or the maximum annual incentive otherwise established by the Compensation Committee for each executive officer. Our Chief Executive Officer retains the discretion to approve increases (up to 10%, subject to Compensation Committee consent) and decreases (up to 20%) in the size of the incentive pool. However, no individual may receive an award in excess of the maximum amount established by the Compensation Committee (two times his or her target annual incentive).

In the first quarter of 2021, the Compensation Committee set 2021 annual incentive eligibility for our NEOs. For each NEO, annual incentive eligibility was set as a target percentage of the executive’s base salary at year end (and, for Ms. Davies, including her annual foreign service allowance received in connection with her relocation to London). Target annual incentive opportunities for our NEOs for 2021, as a percentage of base salary, remained flat as compared to 2020, with the exception of Mr. Andersen, whose target increased from 100% to 150% as a result of the peer group and executive compensation review processes outlined above. The target annual incentives for each of our NEOs for 2021 are shown in the table below:

As explained below, for 2021, the Compensation Committee used a framework (the “Senior Executive Incentive Compensation Plan”) for determining actual annual incentives to be paid if the metric under our Shareholder-Approved Plan was achieved.

2021 Performance Metrics. In the first quarter of 2021, the Compensation Committee determined that 2021 Aon-wide performance would be measured by two components. First, 80% of the performance would be measured by the growth in adjusted operating income (“OI”) for 2021 (as adjusted for unusual or infrequently occurring items) as compared to a 2020 baseline adjusted OI number of $3,150 million. The Compensation Committee retained the discretion to further adjust OI under the plan for extraordinary, unusual, or infrequently occurring items. The Compensation Committee selected OI as the primary measure to emphasize performance of Aon as a whole and directly link executives’ awards to Aon’s key business initiatives of delivering distinctive client value and achieving operational excellence.

Second, 20% of the performance would be measured by the Compensation Committee’s assessment of the Company’s progress against quantitative goals within its I&D initiatives in the recruitment, promotion, education, and representation strategy pillars on a firm-wide basis, as determined by the Inclusion & Diversity Sub-Committee and the Compensation Committee (the “People & Culture” component). This component is intended to be leveraged (0% to 200%) and success is measured by examining the number of pre-established goals met and the degree of over or underperformance across the goals established by the Compensation Committee. This assessment is made in consultation with the Inclusion & Diversity Sub-Committee utilizing informed discretion.

In addition, the Compensation Committee set a minimum achievement threshold at 70% of the 2020 adjusted OI, or $2,205 million. The Compensation Committee set the minimum threshold at 70% because it believed performance below that

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level would not create enough value for the Company’s shareholders and, therefore, should not result in annual incentive payments. If the minimum achievement threshold is satisfied, an annual incentive pool may be funded as described below under “Determining 2021 Annual Incentives.”

2021 Actual Performance. The Company’s adjusted OI for 2021 was $3,673 million for purposes of determining 2021 annual incentives, which exceeded the minimum threshold of 70% established under our Shareholder-Approved Plan. The $3,673 million of adjusted OI was 16.6% greater than 2020 adjusted OI of $3,150 million, resulting in a performance factor of 114.6% for the financial component.

The Compensation Committee reviewed the firm’s progress against a robust set of quantitative goals demonstrating progress in the firm’s inclusion and diversity strategy. Strong progress was made in promoting colleagues equitably by exceeding the pre-established quantitative goals to eliminate promotion rate gaps across the talent pipeline for women globally and for colleagues from racially/ethnically diverse backgrounds in the United States. Similarly strong progress was made in the education strategy pillar as colleagues’ views of the firm’s advocacy for diversity, equity, and inclusion exceeded the pre-established quantitative goal and perception gaps amongst cohorts were reduced. Representation of women in senior leadership grew more than in any prior year, while representation of colleagues from racially/ethnically diverse backgrounds in the United States within upper management and senior leadership continued to rise. Finally, the firm hired colleagues from racially/ethnically diverse backgrounds in leadership positions at rates that exceeded current levels of representation, and new practices were established to continue improvement, though the Committee views this strategy pillar as an ongoing opportunity. Based on its assessment of progress around these goals, the Compensation Committee determined that the performance factor was 125% for the People & Culture component, and that the overall weighted performance factor was 116.7%.

Determining 2021 Annual Incentives. In accordance with our Shareholder-Approved Plan, the Senior Executive Incentive Compensation Plan would not be funded for 2021 unless Aon achieved the minimum threshold of 70% of the 2020 baseline OI. After determining that this minimum threshold had been achieved, the Compensation Committee met in February 2022 to determine the funding status of the incentive pool for 2021. After application of the formula guidelines described above, the total incentive pool reserved for participating members of the Company’s senior management team (including our NEOs) was determined to be approximately $10.9 million. None of the NEOs received their maximum annual incentive of two times their target annual incentive. Each NEO received in the range of 120% to 133% of their target annual incentive, including Mr. Case, who received an annual incentive of $3.75 million, or 125% of his target annual incentive.

The following table sets forth the actual annual incentive paid to each of our NEOs under the Senior Executive Incentive Compensation Plan for the year:

In determining annual incentives for our NEOs, the Compensation Committee (or, with respect to Mr. Case, the independent members of the Board) considered Mr. Case’s compensation recommendations for the NEOs (other than himself), business and financial results, individual delivery of key strategic initiatives, personal leadership qualities, and annual incentives for similarly situated executives of our 2021 peer group members.

Regarding Mr. Case, the independent directors of the Board determined that, under his leadership, the Company delivered impressive progress across the four key financial metrics that we report to shareholders: organic revenue growth, adjusted operating margin, adjusted diluted earnings per share, and free cash flow. Organic revenue growth was 9%, operating margin on an adjusted basis increased 160 basis points to 30.1%, adjusted diluted earnings per share increased 22% to $12.00, and free cash flow was $2.0 billion. During 2021, the firm deployed nearly $4.0 billion of capital through share repurchases and

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dividends. Under Mr. Case’s leadership, Aon also made progress on strategic initiatives including our future Aon United strategy, establishing a new operating model and senior leadership team, advancing its strategy to improve inclusion and diversity, launching the updated Aon brand, increasing leverage of the Aon Business Services platform, and scaling commercialized innovation. Mr. Case led execution of these initiatives and accelerated the momentum of Aon United following the termination of the proposed combination with Willis Towers Watson. Mr. Case demonstrated exemplary leadership in continuing to navigate the COVID-19 pandemic, continued social upheaval, the most competitive talent market in recent years and other challenges to achieve continued record-high colleague engagement measures, retention rates in line with pre-pandemic levels, and meaningful progress on inclusion and diversity initiatives, setting the tone at the top of the organization in naming an Aon Executive Committee with 45% female representation.

Regarding Ms. Davies, the Compensation Committee determined that her individual efforts contributed substantially to the Company’s impressive business and financial results in 2021, including the four key financial metrics that we report to shareholders: organic revenue growth, adjusted operating margins, adjusted diluted earnings per share, and free cash flow. Further, she led our disciplined approach to capital and balance sheet management, realizing the completion of $3.5 billion in share repurchase, a record high 27.4% return on invested capital, and the issuance of $1.1 billion in incremental debt while maintaining our investment grade credit rating. Ms. Davies was heavily engaged in developing the future Aon United strategy and accelerated this strategy following the termination of the proposed combination. She led extensive outreach to shareholders to effectively communicate strategy and financial results. Early in the year, Ms. Davies assumed responsibility for the firm’s physical and information security, and delivered enhanced capabilities through standardization, support for security operations and incident response, and colleague awareness. Ms. Davies continues to be a visible role model for inclusive people leadership and championed initiatives that drove colleague engagement, retention, and diversity throughout the year.

Regarding Mr. Andersen, the Compensation Committee determined that his individual efforts contributed substantially to the Company’s impressive business and financial results in 2021, including the four key financial metrics that we report to shareholders: organic revenue growth, adjusted operating margins, adjusted diluted earnings per share, and free cash flow. Mr. Andersen was critical in helping deliver strong organic growth of 11% in Commercial Risk, 10% in Health, 8% in Reinsurance, and 2% in Wealth. Mr. Andersen led development of the future Aon United strategy and drove accelerated adoption of this strategy following the termination of the proposed combination, resulting in an updated Aon United Blueprint, client value creation model, and go-to-market strategy recognizing the differentiated needs of both our existing client base and the expanded addressable market. Mr. Andersen reorganized the senior leadership of the firm and appointed a new and diverse leadership team under a redesigned operating model to realize the full power of Aon United. Mr. Andersen’s leadership was instrumental in supporting colleague engagement and retention in a competitive talent marketplace, and in setting a standard for inclusive leadership with business leaders.

Regarding Ms. Stevens, the Compensation Committee determined that her individual efforts contributed substantially to the attraction, retention, and motivation of industry-leading talent and enabled the Company’s impressive business and financial results in 2021. Ms. Stevens’s leadership through the continued pandemic has resulted in expanded resources to prioritize colleague wellbeing, development of our Smart Working strategy and return to the office approach, and in the significant expansion of the reach and impact of our learning programs to support the Aon United culture, leadership, and inclusion. These and other actions have allowed us to maintain record-high colleague engagement and retention in a competitive talent market. Ms. Stevens led the adoption of the new global firm operating model and the appointment of more than 1,000 leaders into new roles while also achieving material improvements in the diversity of our senior leadership. Ms. Stevens extended her leadership further during the year to assume responsibility for the Human Capital Solutions business, where she achieved significant revenue growth, drove margin expansion, and deepened our service offerings and client base.

Regarding Mr. Zeidel, the Compensation Committee determined that his individual efforts in advancing the firm’s commercial initiatives and protecting the firm from risks enabled the Company’s impressive business and financial results in 2021. Mr. Zeidel navigated Aon through the challenging legal and regulatory dynamics surrounding the proposed combination and termination of the transaction, working tirelessly to protect the best interests of colleagues, clients, and shareholders throughout. Mr. Zeidel enhanced the firm’s global approach to enterprise risk management and made significant improvements to the management of privacy risk globally, including compliance with complex regulatory regimes. He has provided counsel and leadership with respect to the fragmented public health mandates associated with the pandemic as we

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established our Smart Working strategy and contemplated our return to office approach. Mr. Zeidel has been a passionate advocate for underserved communities and under his leadership, the firm’s law and compliance department has led community service and pro bono initiatives, including in the areas of criminal justice, disability law, and COVID-19 relief in India.

Executive and Relocation Benefits

Executive Benefits. In addition to our broad-based employee benefit programs that are available to our employees generally (such as health coverage, 401(k) plan, etc.), each of our NEOs is eligible to participate in a deferred compensation program and a supplemental savings plan. Only Mr. Andersen participates in our defined benefit pension plan and the supplemental pension program (each of which are frozen to new participation) because each other NEO was hired after the Aon Pension Plan was closed to new hires in 2004. Additional information regarding these qualified and nonqualified plan benefits is set forth under the headings “Pension Benefits in Fiscal Year 2021” and “Nonqualified Deferred Compensation in Fiscal Year 2021” contained in this proxy statement. We also provide an executive health screening program available to all of our NEOs and the other members of our senior management team.

Relocation Benefits. In 2021, we continued to provide relocation benefits resulting from the relocation of our headquarters to London, United Kingdom in 2012 (the “2012 Redomestication”) to certain of our NEOs. The Aon group global operational headquarters remained in London following the Company’s reorganization as a public company organized under the laws of Ireland in April 2020 (the “Reorganization”). The parent company Aon plc is resident in Dublin. Relocation benefits are customary for expatriate assignments for us and other employers in our industry. The Compensation Committee approved certain benefits for the relocated executives after consulting with its Compensation Consultant, and each relocated executive has signed an international assignment letter with Aon that sets forth the relocation benefits available to him or her. The relocation packages for our NEOs are intended to keep them “whole” on a total rewards basis, including with respect to any additional taxes incurred as a result of the relocation, be transparent and equitable, and reflect competitive practices and benchmarks of industry peers. The Compensation Committee periodically reviews the relocation packages of our executives. These benefits are provided pursuant to international assignment letters with our NEOs on assignment, which are described in more detail under the heading “International Assignment Letters.”

The compensation received in the form of such benefits is reflected in the Summary Compensation Table for Fiscal Years 2021, 2020, and 2019.

Post-Termination Compensation

We believe that providing severance and change in control severance benefits is important to recruit talented employees and secure the continued employment and dedication of our existing employees. A significant number of the companies with which we compete for talent have similar arrangements in place for their senior executives. While we consider these benefits to be important, the terms of these benefits are not considered as part of the compensation strategy when the Compensation Committee annually determines the compensation for the NEOs. Additional information about post-termination compensation is set forth in the section captioned “Potential Payments on Termination or Change in Control” contained in this proxy statement.

Severance Benefits Upon Change in Control. Our NEOs, other than Mr. Case, are eligible for change in control severance benefits under our Senior Executive Combined Severance and Change in Control Plan (referred to throughout this CD&A and the accompanying compensation tables as the “Combined Severance Plan”). The Combined Severance Plan provides that covered executives would receive certain severance benefits upon qualifying terminations of employment in connection with or within two years following a change in control of Aon. Thus, the Combined Severance Plan requires a “double trigger”—a qualifying change in control of Aon and a qualifying termination of the executive’s employment—for severance benefits to become payable. Mr. Case, who is not covered under the Combined Severance Plan, is party to an individual change in control severance agreement with the Company that also provides certain severance benefits upon a qualifying termination in connection with or within two years following a change in control of Aon. Neither the Combined Severance Plan nor Mr. Case’s individual agreement provides for excise tax gross-up protection in the event the executive becomes subject to tax under Section 280G of the Code in connection with such double trigger.

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Additional information regarding the change in control arrangements for our NEOs is set forth in the section captioned “Potential Payments on Termination or Change in Control” contained in this proxy statement.

Severance Benefits Pursuant to Employment Agreements and Combined Severance Plan. We have entered into agreements with certain executive officers that provide for post-employment severance benefits and transitional compensation if the officer’s employment terminates for a qualifying event or circumstance unrelated to a change in control of Aon, such as being terminated without “cause,” as such term is defined in the operative agreement. To the extent that our NEOs are not party to an individual employment agreement providing for severance benefits, those individuals are eligible to receive severance benefits under the Combined Severance Plan. During 2021, each of our NEOs had an employment agreement providing for severance benefits or was eligible to receive severance benefits under the Combined Severance Plan. Additional information regarding such post-employment severance or transitional compensation for Mr. Case and the other NEOs is set forth in the section captioned “Potential Payments on Termination or Change in Control” contained in this proxy statement.

Risk Assessment of Compensation Policies and Practices

We believe that we maintain an appropriate level of prudence associated with our compensation practices and will continue to do so. We engage in a process to evaluate whether our executive and broad-based compensation programs contribute to unnecessary risk-taking. This includes a detailed annual assessment by the Compensation Consultant. We concluded that the risks arising from these programs are not reasonably likely to have a material adverse effect on the Company. In the first quarter of 2022, Meridian independently assessed our compensation practices for 2021 and concluded that they reflect appropriate balance and incorporate appropriate policies and oversight to mitigate imprudent risk-taking.

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Compensation Committee Report

The Organization and Compensation Committee of the Board has reviewed and discussed with management the Compensation Discussion and Analysis required by Item 402(b) of Regulation S-K and set forth in this proxy statement.

Based on its review and discussions with management, the Organization and Compensation Committee recommended to the Board that the Compensation Discussion and Analysis be included in this proxy statement and incorporated into Aon’s Annual Report on Form 10-K.

This Report is provided by the Organization and Compensation Committee, which is composed entirely of the following independent directors:

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Executive Compensation

The executive compensation disclosure contained in this section reflects compensation information for the years ended December 31, 2021, December 31, 2020, and December 31, 2019 with respect to our NEOs for all years in which each NEO served in that capacity. The following Summary Compensation Table contains compensation information for the following NEOs: (1) Mr. Case, who served as our Chief Executive Officer during 2021, (2) Ms. Davies, who served as our Chief Financial Officer during 2021, and (3) Mr. Andersen, Ms. Stevens, and Mr. Zeidel, who were our three other most highly compensated executive officers serving as of December 31, 2021. No compensation prior to 2021 is included for Ms. Stevens or Mr. Zeidel because they were not named executive officers for those years.

Summary Compensation Table for Fiscal Years 2021, 2020 and 2019

In 2019-2021, each of our NEOs received awards of performance share units under the LPP with a grant date fair value as set forth in the table below.

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Employment Agreements and Other Compensation Agreements

Mr. Case’s Employment Agreement

We are party to an Amended and Restated Employment Agreement with Gregory C. Case pursuant to which he serves as our Chief Executive Officer. The current term of Mr. Case’s agreement continues through April 1, 2026, unless terminated earlier or extended. The agreement also provides that Mr. Case will be nominated for re-election as a member of the Board at each annual general meeting of shareholders during the period of his employment.

Mr. Case’s agreement provides for an initial base salary of $1,500,000, subject to adjustment at the discretion of the Board, and a target annual incentive bonus of not less than 200% of base salary, subject to the provisions of our Shareholder-Approved Plan. The Board retains the discretion to determine Mr. Case’s actual bonus payment. In the first quarter of 2022, the Compensation Committee performed its annual compensation review (as described above under “The Executive Compensation Process”) and adjusted Mr. Case’s target annual incentive to 250% of base salary.

In addition, Mr. Case’s agreement provides that he will be provided with life insurance coverage in an amount equal to no less than $5,000,000 during the term of the agreement. Under the agreement, Mr. Case has also agreed to maintain an investment position in Aon Class A Ordinary Shares equal to no less than 20 times his annual base salary.

Ms. Davies’s Employment Agreement

We are party to an Employment Agreement with Christa Davies pursuant to which she serves as our Executive Vice President and Chief Financial Officer. The current term of Ms. Davies’s agreement continues through April 1, 2026, unless terminated earlier or extended. The agreement provides for an initial base salary, which has subsequently been adjusted by our Compensation Committee as permitted under the agreement, and a target annual incentive bonus of 150% of her base salary and foreign service allowance. In the first quarter of 2022, the Compensation Committee performed its annual compensation review (as described above under “The Executive Compensation Process”) and adjusted Ms. Davies’s target annual incentive to 200% of base salary.

Mr. Andersen’s Employment Letter

We have provided Eric Andersen an employment letter pursuant to which he serves as our President. The letter provides that Mr. Andersen’s continued employment with us is on an at-will basis, and that he is eligible to participate in our Combined Severance Plan. Mr. Andersen’s letter also provides for an initial base salary and an initial target annual bonus, both of which have been adjusted by the Compensation Committee as permitted under the letter. In early 2021, the Compensation Committee approved an increase to Mr. Andersen’s target annual incentive from 100% to 150%. In the first quarter of 2022, the Compensation Committee performed its annual compensation review (as described above under “The Executive Compensation Process”) and adjusted Mr. Andersen’s target annual incentive to 200% of base salary.

Ms. Stevens’s Employment Letter

We have provided Lisa Stevens an employment letter pursuant to which she serves as our Chief People Officer and Head of Human Capital Solutions. The letter provides that Ms. Stevens’s continued employment with us is on an at-will basis, and that she is eligible to participate in our Combined Severance Plan. Ms. Stevens’s letter also provides for an initial base salary, which has subsequently been adjusted by our Compensation Committee as permitted under the letter, a target annual bonus

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of 100% of her base salary, and an initial target long-term incentive award of 150% of her base salary. In the first quarter of 2022, the Compensation Committee performed its annual compensation review (as described above under “The Executive Compensation Process”) and adjusted Ms. Stevens’s target annual incentive to 150% of her base salary.

Mr. Zeidel’s Employment Letter

We have provided Darren Zeidel an employment letter pursuant to which he serves as our Executive Vice President, General Counsel, and Company Secretary. The letter provides that Mr. Zeidel’s continued employment with us is on an at-will basis, and that he is eligible to participate in our Combined Severance Plan. Mr. Zeidel’s letter also provides for an initial base salary, which has subsequently been adjusted by our Compensation Committee as permitted under the letter, a target annual bonus of 100% of his base salary, and an initial target long-term incentive award of 150% of his base salary.

International Assignment Letters

In connection with the Company’s 2012 Redomestication, we entered into international assignment letters with each of Mr. Case and Ms. Davies. These letters describe the international assignments and set forth the relocation benefits to the executives, which are described below. The letters are not intended to diminish the rights of the executives under their current employment arrangements; however, the letters provide by their terms that the executives’ acceptance of their international assignments, and repatriation thereafter, will not give rise to any right to terminate for good reason (as such term is defined in the applicable executive’s employment agreement, if applicable).

The letters for Mr. Case and Ms. Davies were amended and extended in July 2014 for an additional two years, on July 1, 2016 for an additional two years, and on each July 1 of 2018 through 2021 for an additional year.

Depending on each executive’s personal circumstances, and as disclosed in the tables above, the relocation packages, as amended, generally provide some or all of the following benefits:

All of the relocation benefits are subject to recoupment if the executive officer resigns employment with the Company within two years of commencing the international assignment, or 12 months after the end of the assignment, and becomes employed by a direct competitor of the Company.

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Grants of Plan-Based Awards in Fiscal Year 2021

The following table provides information on non-equity incentive plan compensation, restricted share unit awards, and performance share unit awards granted in 2021 to each of the NEOs.

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Outstanding Equity Awards at 2021 Fiscal Year-End

The following table sets forth information regarding outstanding restricted share units and performance share units held by each of our NEOs on December 31, 2021. See “Potential Payments and Benefits on Termination or Change in Control” for information regarding the impact of certain employment termination scenarios on outstanding equity awards.

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