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INCOME TAXES - STATUTORY RATE RECONCILIATION (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2026 | Jun. 30, 2025 | Jun. 30, 2026 | Jun. 30, 2025
Statutory rate reconciliation, amount |  |  |  |
Income before income taxes | $ 328.0 | $ 262.5 | $ 1,187.2 | $ 1,048.7
United States federal statutory income tax rate, amount | 68.5 | 55.6 | 248.6 | 220.4
State and local income taxes net of federal tax effect, amount | 18.7 | 15.2 | 68.0 | 63.7
Tax credits, amount |  |  |  |
PTCs, net, amount | (38.8) | (40.5) | (168.5) | (160.6)
Other, amount | (1.5) | (1.3) | (5.4) | (4.6)
Nontaxable or nondeductible items, amount |  |  |  |
AFUDC-Equity, amount | (7.8) | (2.7) | (26.9) | (11.2)
Other, amount | 2.2 | 2.3 | 8.0 | 5.7
Changes in unrecognized tax benefits, amount |  |  |  |
Changes in unrecognized tax benefits, amount |  |  | 0.0 | 0.1
Other adjustments, amount |  |  |  |
Federal excess deferred tax amortization, amount | (6.8) | (6.8) | (25.3) | (25.5)
Other, net, amount | (7.5) | (2.3) | (18.4) | (7.8)
Total income tax expense, amount | $ 27.0 | $ 19.5 | $ 80.1 | $ 80.2
Statutory rate reconciliation, percent |  |  |  |
United States federal statutory income tax rate, percent | 21.00% | 21.00% | 21.00% | 21.00%
State and local income taxes net of federal tax effect, percent | 5.70% | 5.80% | 5.70% | 6.10%
Tax credits, percent |  |  |  |
PTCs, net, percent | (12.00%) | (15.30%) | (14.20%) | (15.30%)
Other, percent | (0.40%) | (0.50%) | (0.50%) | (0.40%)
Nontaxable or nondeductible items, percent |  |  |  |
AFUDC-Equity, percent | (2.40%) | (1.00%) | (2.30%) | (1.10%)
Other, percent | 0.70% | 0.90% | 0.70% | 0.50%
Changes in unrecognized tax benefits, percent |  |  |  |
Changes in unrecognized tax benefits, percent |  |  | 0.00% | 0.00%
Other adjustments, percent |  |  |  |
Federal excess deferred tax amortization, percent | (2.10%) | (2.60%) | (2.10%) | (2.50%)
Other, net, percent | (2.30%) | (0.90%) | (1.60%) | (0.70%)
Total income tax expense, percent | 8.20% | 7.40% | 6.70% | 7.60%
Rate2018And2019 | Public Service Commission of Wisconsin (PSCW) | Tax Cuts And Jobs Act Of 2017 |  |  |  |
Income Taxes |  |  |  |
Income statement impact of amortizing deferred tax benefits | $ 0.0 | $ 0.0 | $ 0.0 | $ 0.0

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