Income Taxes

3 Months Ended

Mar. 31, 2026

Income Tax Disclosure [Abstract]

Income Taxes

6. Income Taxes

Total income tax expense from operations differs from the amount computed by applying the statutory federal income tax rate to income before income tax expense.

Effective income tax reconciliation:

	Three Months Ended March 31
(Millions of Dollars)	2026		2025
Income before income taxes (domestic)	$	64	$	38
Federal statutory rate impact	13		8
(Decreases) increases in tax from:
Tax credits
PTCs (a)	(31)		(29)
Regulatory adjustments (b)
AFUDC equity	(3)		(1)
Plant related excess deferred taxes	(1)		(1)
Other	1		—
State income taxes, net of federal tax effect (c)	1		1
Other	—		1
Income tax benefit	$	(20)	$	(21)

	Three Months Ended March 31
	2026		2025
Federal statutory rate	21.0	%	21.0	%
(Decreases) increases in tax from:
Tax credits
PTCs (a)	(49.2)		(78.0)
Other	(0.2)		(0.3)
Regulatory adjustments (b)
AFUDC equity	(4.1)		(1.6)
Plant related excess deferred taxes	(1.8)		(3.0)
Other	0.9		0.8
State income taxes, net of federal tax effect (c)	1.9		2.2
Other	0.2		3.6
Effective income tax rate	(31.3)	%	(55.3)	%

(a)Wind PTCs (net of transfer discounts) are generally credited to customers (reduction to revenue) and do not materially impact earnings.

(b)Regulatory adjustments primarily relate to the credit of plant related excess deferred taxes to customers for tax rate increases 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.

(c)State and local income taxes are primarily made up of the following jurisdictions: New Mexico, Texas