UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): June 16, 2023

Aon plc

(Exact name of registrant as specified in its charter)

Metropolitan Building, James Joyce Street

Dublin 1, Ireland D01 K0Y8

(Address of principal executive offices)

Registrant’s telephone number, including area code: +353 1 266 6000

Former name or former address, if changed since last report: Not Applicable

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2 below):

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

On June 16, 2023, Aon Corporation, an indirect, wholly owned subsidiary of Aon plc (“Aon Corporation”), and Christa Davies entered into an amendment (the “Davies Amendment”) to the international assignment letter agreement dated July 1, 2016 between Aon Corporation and Ms. Davies (the “Davies International Assignment Letter”). The Davies Amendment extends the term of the Davies International Assignment Letter, which was set to expire on June 30, 2023, to expire on June 30, 2024.

On June 16, 2023, Aon Corporation and Gregory C. Case entered into an amendment (the “Case Amendment”) to the international assignment letter agreement dated July 1, 2016 between Aon Corporation and Mr. Case (the “Case International Assignment Letter”). The Case Amendment extends the term of the Case International Assignment Letter, which was set to expire on June 30, 2023, to expire on June 30, 2024.

The foregoing summaries are qualified in their entirety by reference to the Davies Amendment and the Case Amendment, copies of which are attached as Exhibits 10.1 and 10.2, respectively, to this Current Report on Form 8-K and incorporated herein by reference.

On June 16, 2023, Aon plc held its 2023 Annual General Meeting of Shareholders (the “Annual Meeting”) at which the Company’s shareholders approved the Aon plc 2011 Incentive Plan, as amended and restated (the “Amended Plan”). The Amended Plan increases by 3,800,000 the maximum number of Class A Ordinary Shares available for issuance. The Amended Plan also removes certain provisions relating to Section 162(m) of the Internal Revenue Code that are no longer applicable following the elimination of the performance-based compensation exception to Section 162(m)’s limitation on deductibility by the Tax Cuts and Jobs Act, removes certain legacy provisions relating to the 2012 Redomestication that are no longer applicable, extends the date until which awards may be granted under the Amended Plan to April 19, 2033, and makes certain other clarifying changes.

Further information regarding the Amended Plan was provided in the Company’s definitive proxy statement for the Annual Meeting filed with the Securities and Exchange Commission on April 28, 2023 (the “Proxy Statement”) in the section entitled “Proposal 7 — Resolution to Approve the Aon plc 2011 Incentive Plan, As Amended and Restated”.

The foregoing summary of the Amended Plan is qualified in its entirety by reference to the complete text of the Amended Plan, a copy of which is attached hereto as Exhibit 10.3 to this Current Report on Form 8-K and incorporated herein by reference.

The Company held its Annual Meeting on June 16, 2023. A total of 185,627,827 Class A Ordinary shares, or 90.81% of the total shares entitled to vote, were represented at the Annual Meeting in person or by proxy.

Shareholders voted on the following seven proposals at the Annual Meeting, all of which are described in the Proxy Statement, and cast their votes as described below:

Based on the voting results on Item 3, the Company intends to hold the advisory vote on named executive officer compensation once every year. The Company intends to continue holding such advisory votes once every year until the next required advisory vote on the frequency of advisory votes on named executive officer compensation.

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(d) Exhibits.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.