Income Taxes (Tables)

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Schedule of Income From Continuing Operations Before Income Tax

Income before income tax and the provision for income tax consist of the following (in millions):

	Years Ended December 31
	2025		2024		2023
Income before income taxes:
Ireland	$	162	$	52	$	31
U.K.	663		782		338
U.S.	1,220		854		219
Other	2,714		1,774		2,581
Total	$	4,759	$	3,462	$	3,169
Income tax expense:
Current:
Ireland	$	12	$	13	$	4
U.K.	164		233		185
U.S. federal	422		292		240
U.S. state and local	110		79		74
Other	442		436		411
Total current tax expense	$	1,150	$	1,053	$	914
Deferred tax expense (benefit):
Ireland	$	(1)	$	—	$	—
U.K.	(44)		(169)		(116)
U.S. federal	(92)		(83)		(126)
U.S. state and local	20		(71)		(39)
Other	(24)		12		(92)
Total deferred tax expense (benefit)	$	(141)	$	(311)	$	(373)
Total income tax expense	$	1,009	$	742	$	541

Schedule of Reconciliation of the Income Tax Provisions Based on its Domicile and Statutory Rate and Irish Statutory Corporate Tax Rate

The Company performs a reconciliation of the income tax provisions based on its domicile and statutory rate at each reporting period. The reconciliation of the income tax provisions based on the Irish statutory corporate tax rate of 25% to the provisions reflected in the Consolidated Financial Statements is as follows:

	Year Ended December 31
	2025
	$	%
Provision for income taxes at the Irish statutory tax rate	$1,190	25.0%
Foreign Tax Effects
United States
State and local income taxes, net of federal income tax effect	83	1.7
Effect of cross-border tax laws	(60)	(1.3)
Other	(2)	—
Bermuda
Deferred tax adjustment	(143)	(3.0)
Changes in valuation allowances	114	2.4
Other	(1)	—
Singapore
Incentive	(120)	(2.5)
Statutory tax rate difference between Singapore and Ireland	(101)	(2.1)
Other	(37)	(0.8)
Other foreign jurisdictions	(5)	(0.1)
Changes in unrecognized tax benefits	121	2.5
Other adjustments	(30)	(0.6)
Income tax expense and effective tax rate	$1,009	21.2%

Below is a reconciliation of the Irish statutory corporate tax rate and the Company’s effective tax rate for the years ended December 31, 2024 and 2023.

	Years Ended December 31
	2024	2023
Statutory tax rate	25.0%	25.0%
U.S. state income taxes, net of U.S. federal benefit	0.7	0.6
Taxes on international operations (1)	(9.3)	(11.2)
Nondeductible expenses	1.8	3.2
Adjustments to prior year tax requirements	0.8	0.5
Deferred tax adjustments, including statutory rate changes	(0.1)	(0.3)
Deferred tax adjustments, international earnings	1.1	0.7
Adjustments to valuation allowances	(0.1)	(2.5)
Change in uncertain tax positions	2.3	2.6
Excess tax benefits related to shared based compensation (2)	(0.7)	(1.6)
Capital and other losses	—	—
Other — net	(0.1)	0.1
Effective tax rate	21.4%	17.1%

(1)The Company determines the adjustment for taxes on international operations based on the difference between the statutory tax rate applicable to earnings in each foreign jurisdiction and the enacted rate of 25.0% and 25.0% at December 31, 2024, and 2023, respectively. The benefit to the Company’s effective income tax rate from taxes on international operations relates to benefits from lower-taxed global operations, primarily due to the use of global funding structures and the tax holiday in Singapore.

(2)Excess tax benefits and deficiencies from share-based payment transactions are recognized as income tax expense or benefit in the Company’s Consolidated Statements of Income.

Schedule of Cash Flow, Supplemental Disclosures

Cash taxes paid (net of refunds) by jurisdiction:

	Year Ended December 31
	2025
Federal (Ireland)	$	11
Foreign
United States federal	$	247
United Kingdom	$	240
Canada	$	74
Singapore	$	54
All other foreign	$	410
Cash taxes paid (net of refunds)	$	1,036

Schedule of Components of Aon's Deferred Tax Assets and Liabilities

The components of the Company’s deferred tax assets and liabilities are as follows (in millions):

As of December 31	2025		2024
Deferred tax assets:
Net operating loss, capital loss, interest, and tax credit carryforwards	$	1,682	$	1,576
Employee benefit plans	325		359
Lease liabilities	157		171
Other accrued expenses	166		176
Federal and state benefit of interest from uncertain tax positions	127		99
Accrued interest	16		102
Deferred revenue	34		31
Investment basis differences (1)	5		(42)
Other	58		56
Total	2,570		2,528
Valuation allowance on deferred tax assets	(306)		(202)
Total	$	2,264	$	2,326
Deferred tax liabilities:
Intangibles and property, plant and equipment	$	(1,367)	$	(1,512)
Deferred costs	(184)		(160)
Lease right-of-use asset	(125)		(139)
Unremitted earnings	(55)		(66)
Other accrued expenses	(23)		(21)
Unrealized foreign exchange gains	(41)		(36)
Other	(61)		(57)
Total	$	(1,856)	$	(1,991)
Net deferred tax asset	$	408	$	335

(1)The balance was in a liability position for the comparable period.

Schedule of Deferred Income Taxes (Assets and Liabilities Netted by Jurisdiction) as Classified in the Consolidated Statements of Financial Position

Deferred income taxes (assets and liabilities have been netted by jurisdiction) have been classified in the Consolidated Statements of Financial Position as follows (in millions):

As of December 31	2025	2024
Deferred tax assets — non-current	748	654
Deferred tax liabilities — non-current	(340)	(319)
Net deferred tax asset	408	335

Schedule of Operating and Capital Loss Carryforwards

The Company had the following carryforwards (in millions):

As of December 31	2025		2024
U.K.
Operating loss carryforwards	$	1,587	$	1,499
Capital loss carryforwards	$	593	$	557
Interest carryforwards	$	112	$	85
U.S.
Federal operating loss carryforwards	$	1	$	2
Federal interest carryforwards	$	4,117	$	3,743
Federal foreign tax credit carryforwards	$	25	$	29
State operating loss carryforwards	$	1,348	$	1,822
State interest carryforwards	$	2,427	$	2,303
Other Non-U.S.
Operating loss carryforwards	$	453	$	339
Capital loss carryforwards	$	10	$	9
Interest carryforwards	$	176	$	126

Schedule of Reconciliation of the Beginning and Ending Amount of Unrecognized Tax Benefits

The following is a reconciliation of the Company’s beginning and ending amount of uncertain tax positions (in millions):

	2025		2024
Balance at January 1	$	722	$	637
Additions based on tax positions related to the current year	52		39
Additions for tax positions of prior years	14		1
Reductions for tax positions of prior years	(12)		(5)
Settlements	—		(1)
Business combinations	(1)		61
Lapse of statute of limitations	(8)		(10)
Foreign currency translation	—		—
Balance at December 31	$	767	$	722