v3.26.1
Income Taxes (Tables)
 6 Months Ended
Jun. 30, 2026
Income Tax Disclosure [Abstract]  
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
Effective income tax reconciliation:
Six Months Ended June 30
(Millions of Dollars)20262025
Income before income taxes (domestic)$136 $88 
Federal statutory rate impact29 18 
(Decreases) increases in tax from:
Tax credits
Other(1)— 
Regulatory adjustments (a)
AFUDC equity(2)(2)
Plant related excess deferred taxes(1)(1)
State income taxes, net of federal tax effect (b)
8 5 
Other(1)— 
Income tax expense$32 $20 
Six Months Ended June 30
20262025
Federal statutory rate21.0 %21.0 %
(Decreases) increases in tax from:
Tax credits
Other(0.6)(0.5)
Regulatory adjustments (a)
AFUDC equity(1.8)(2.4)
Plant related excess deferred taxes(0.9)(1.4)
Other0.3 0.3 
State income taxes, net of federal tax effect (b)
5.5 5.2 
Other— 0.5 
Effective income tax rate23.5 %22.7 %
(a)Regulatory adjustments primarily relate to the credit of plant related excess deferred taxes to customers for tax rate changes as well as the capitalization of AFUDC equity for book purposes only. Income tax benefits associated with the credit of excess deferred taxes are offset by corresponding revenue reductions.
(b)State and local income taxes are primarily Wisconsin state taxes.