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v3.25.4

Income Taxes (Tables) | 12 Months Ended
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Dec. 31, 2025
Income Tax Disclosure [Abstract] |
Schedule of total income tax benefit (expense) | The following table presents the total income tax (expense) benefit for the years ended December 31, 2025, 2024 and 2023:
|  | Year Ended December 31,
Millions |  | 2025 |  | 2024 |  | 2023
Current income tax (expense) benefit: |  |  |  |  |  |
U.S. federal |  | $ | (12.2) |  |  | $ | (6.3) |  |  | $ | (12.6) |
State |  | (2.4) |  |  | (.4) |  |  | (2.2) |
Non-U.S. |  | (20.2) |  |  | (14.8) |  |  | (16.6) |
Total current income tax (expense) benefit |  | (34.8) |  |  | (21.5) |  |  | (31.4) |
Deferred income tax (expense) benefit: |  |  |  |  |  |
U.S. federal |  | (10.7) |  |  | (18.8) |  |  | (13.2) |
State |  | (10.1) |  |  | 2.7 |  |  | (3.8) |
Non-U.S. |  | (71.3) |  |  | 5.0 |  |  | 63.9 |
Total deferred income tax (expense) benefit |  | (92.1) |  |  | (11.1) |  |  | 46.9 |
Total income tax (expense) benefit |  | $ | (126.9) |  |  | $ | (32.6) |  |  | $ | 15.5 |
Schedule of U.S. federal statutory income tax rate and actual effective tax rate on pre-tax income | The following table presents a reconciliation of taxes calculated for 2025, 2024 and 2023 using the 21% U.S. federal statutory rate (the tax rate at which the majority of White Mountains’s worldwide operations are taxed) to the income tax (expense) benefit on pre-tax income (loss):
|  | Year Ended December 31,
$ in Millions |  | 2025 |  | 2024 |  | 2023
U.S. federal statutory tax rate |  | $ | (279.0) |  |  | 21.0 | % |  | $ | (66.5) |  |  | 21.0 | % |  | $ | (118.7) |  |  | 21.0 | %
State income taxes, net of federal income tax effect |  | (11.1) |  |  | 0.8 |  |  | 2.2 |  |  | (0.7) |  |  | (5.8) |  |  | 1.0 |
Effects of changes in tax laws or rates enacted in current period |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Effect of cross-border tax laws |  |  |  |  |  |  |  |  |  |  |  |
Withholding tax |  | (2.4) |  |  | 0.2 |  |  | (1.0) |  |  | 0.3 |  |  | (2.3) |  |  | 0.4 |
Branch profits tax |  | (3.9) |  |  | 0.3 |  |  | (2.7) |  |  | 0.8 |  |  | (5.0) |  |  | 0.9 |
Other |  | — |  |  | — |  |  | (.3) |  |  | 0.1 |  |  | — |  |  | — |
Tax credits |  |  |  |  |  |  |  |  |  |  |  |
Foreign tax credit |  | — |  |  | — |  |  | — |  |  | — |  |  | 1.6 |  |  | (0.3) |
Changes in valuation allowances |  | (9.9) |  |  | 0.8 |  |  | (12.3) |  |  | 3.9 |  |  | (1.4) |  |  | 0.3 |
Nontaxable or nondeductible items |  |  |  |  |  |  |  |  |  |  |  |
Members surplus contribution |  | — |  |  | — |  |  | (2.8) |  |  | 0.9 |  |  | (5.7) |  |  | 1.0 |
Noncontrolling interest |  | 6.4 |  |  | (0.5) |  |  | 3.9 |  |  | (1.2) |  |  | 6.8 |  |  | (1.2) |
Non-taxable foreign income |  | 16.0 |  |  | (1.2) |  |  | 1.4 |  |  | (0.5) |  |  | 2.5 |  |  | (0.4) |
Other |  | (6.6) |  |  | 0.5 |  |  | (4.0) |  |  | 1.3 |  |  | 1.8 |  |  | (0.3) |
Changes in unrecognized tax benefits |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Foreign tax effects |  |  |  |  |  |  |  |  |  |  |  |
United Kingdom |  |  |  |  |  |  |  |  |  |  |  |
Statutory tax rate difference between U.K. and U.S. |  | (3.2) |  |  | 0.2 |  |  | (2.6) |  |  | 0.8 |  |  | (2.0) |  |  | 0.4 |
Other |  | (1.0) |  |  | 0.1 |  |  | 2.9 |  |  | (0.9) |  |  | (.2) |  |  | — |
Luxembourg |  |  |  |  |  |  |  |  |  |  |  |
Statutory tax rate difference between Luxembourg and U.S. |  | (25.3) |  |  | 1.9 |  |  | (.3) |  |  | 0.1 |  |  | (1.9) |  |  | 0.3 |
Changes in valuation allowances |  | 6.6 |  |  | (0.5) |  |  | 4.2 |  |  | (1.3) |  |  | (31.6) |  |  | 5.6 |
Nontaxable or nondeductible items |  |  |  |  |  |  |  |  |  |  |  |
Participation exemption |  | 207.9 |  |  | (15.6) |  |  | — |  |  | — |  |  | 8.5 |  |  | (1.5) |
Write-down of investment |  | — |  |  | — |  |  | — |  |  | — |  |  | 35.4 |  |  | (6.3) |
Other |  | (.1) |  |  | — |  |  | (2.3) |  |  | 0.7 |  |  | (.2) |  |  | — |
Bermuda |  |  |  |  |  |  |  |  |  |  |  |
Statutory tax rate difference between Bermuda and U.S. |  | 53.2 |  |  | (4.0) |  |  | 44.1 |  |  | (13.9) |  |  | 63.4 |  |  | (11.2) |
Enacted changes in tax laws or rates |  | — |  |  | — |  |  | 5.0 |  |  | (1.6) |  |  | 68.0 |  |  | (12.0) |
Nontaxable or nondeductible items |  |  |  |  |  |  |  |  |  |  |  |
Write-down of deferred tax asset |  | (73.0) |  |  | 5.5 |  |  | — |  |  | — |  |  | — |  |  | — |
Other |  | — |  |  | — |  |  | — |  |  | — |  |  | (.1) |  |  | — |
Other foreign jurisdictions |  | (1.5) |  |  | 0.1 |  |  | (1.5) |  |  | 0.5 |  |  | 2.4 |  |  | (0.4) |
Effective rate |  | $ | (126.9) |  |  | 9.6 | % |  | $ | (32.6) |  |  | 10.3 | % |  | $ | 15.5 |  |  | (2.7) | %
Schedule of income taxes paid | The following table presents an outline of the significant components of White Mountains’s U.S. federal, state and non-U.S. tax payments (refunds):
|  | December 31,
Millions |  | 2025 |  | 2024 |  | 2023
U.S. federal taxes |  | $ | 11.1 |  |  | $ | 12.6 |  |  | $ | 22.9 |
State and local taxes |  |  |  |  |  |
California |  | 1.6 |  |  | 2.3 |  |  | — |
New York |  | — |  |  | .4 |  |  | 2.0 |
New York City |  | — |  |  | — |  |  | 2.3 |
Pennsylvania |  | (.5) |  |  | .2 |  |  | .6 |
Other States |  | .8 |  |  | .6 |  |  | 1.4 |
Foreign taxes |  |  |  |  |  |
United Kingdom |  | 16.5 |  |  | 15.1 |  |  | 11.6 |
Other foreign |  | 1.2 |  |  | 3.1 |  |  | 1.9 |
Total income taxes paid |  | $ | 30.7 |  |  | $ | 34.3 |  |  | $ | 42.7 |
Schedule of components of deferred income tax assets and liabilities | The following table presents an outline of the significant components of White Mountains’s U.S. federal, state and non-U.S. deferred tax assets and liabilities:
|  | December 31,
Millions |  | 2025 |  | 2024
Deferred tax assets related to: |  |  |  |
Non-U.S. net operating loss carryforwards |  | $ | 63.1 |  |  | $ | 62.8 |
Incentive compensation |  | 29.3 |  |  | 23.8 |
U.S. federal and state net operating and capital loss carryforwards |  | 15.4 |  |  | 6.4 |
Accrued interest |  | 6.0 |  |  | .2 |
Tax credit carryforwards |  | 3.7 |  |  | 2.8 |
Intangible assets |  | .4 |  |  | 51.5 |
Unearned premiums |  | — |  |  | 20.5 |
Loss reserves |  | — |  |  | 8.5 |
Other items |  | 1.6 |  |  | .9 |
Total gross deferred tax assets |  | 119.5 |  |  | 177.4 |
Less: valuation allowances |  | 95.8 |  |  | 89.2 |
Total net deferred tax assets |  | 23.7 |  |  | 88.2 |
Deferred tax liabilities related to: |  |  |  |
Investment basis difference |  | 87.7 |  |  | 43.5 |
Purchase accounting |  | 43.9 |  |  | 43.9 |
Deferred underwriting |  | 27.5 |  | 24.3 |
Net unrealized investment gains |  | 22.2 |  |  | 19.0 |
Deferred acquisition costs |  | — |  |  | 6.5 |
Other items |  | 2.0 |  |  | 1.2 |
Total deferred tax liabilities |  | 183.3 |  |  | 138.4 |
Net deferred tax asset (liability) |  | $ | (159.6) |  |  | $ | (50.2) |
Schedule of net operating and capital loss carryforwards | The following table presents net operating loss and capital loss carryforwards as of December 31, 2025, the expiration dates and the deferred tax assets thereon:
|  | December 31, 2025
Millions |  | United States |  | Luxembourg |  |  |  |  |  | United Kingdom |  | Israel |  | Total
2026-2030 |  | $ | 3.7 |  |  | $ | — |  |  |  |  |  |  | $ | — |  |  | $ | — |  |  | $ | 3.7 |
2031-2035 |  | .1 |  |  | 29.7 |  |  |  |  |  |  | — |  |  | — |  |  | 29.8 |
2035-2045 |  | — |  |  | 137.2 |  |  |  |  |  |  | — |  |  | — |  |  | 137.2 |
No expiration date |  | 47.2 |  |  | — |  |  |  |  |  |  | .4 |  |  | 100.7 |  |  | 148.3 |
Total |  | $ | 51.0 |  |  | $ | 166.9 |  |  |  |  |  |  | $ | .4 |  |  | $ | 100.7 |  |  | $ | 319.0 |
Gross deferred tax asset |  | $ | 15.4 |  |  | $ | 39.8 |  |  |  |  |  |  | $ | .1 |  |  | $ | 23.2 |  |  | $ | 78.5 |
Valuation allowance |  | (13.4) |  |  | (35.9) |  |  |  |  |  |  | (.1) |  |  | (23.2) |  |  | (72.6) |
Net deferred tax asset |  | $ | 2.0 |  |  | $ | 3.9 |  |  |  |  |  |  | $ | — |  |  | $ | — |  |  | $ | 5.9 |

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