Income Taxes (Tables)

12 Months Ended

Dec. 31, 2024

Schedule of Components of Income Tax Expense (Benefit)

The following table sets forth our provision for income taxes for the periods indicated:


	Year Ended December 31,
	2024		2023		2022
	(Thousands of dollars)
Current income tax provision (benefit)
Federal	$	(68,660)	$	16,551	$	61,745
State	(1,476)		(829)		6,815
Total current income tax provision (benefit)	(70,136)		15,722		68,560
Deferred income tax provision (benefit)
Federal	110,717		21,905		(22,234)
State	(4,195)		2,868		200
Total deferred income tax provision (benefit)	106,522		24,773		(22,034)
Total provision for income taxes	$	36,386	$	40,495	$	46,526

Schedule of Effective Income Tax Rate Reconciliation

The following table is a reconciliation of our income tax provision for the periods indicated:


	Year Ended December 31,
	2024				2023				2022
	(Thousands of dollars, except percentages)
Income before income taxes	$	259,236			$	271,727			$	268,268
Federal statutory income tax rate	21		%		21		%		21		%
Provision for federal income taxes	54,439			21%	57,063			21%	56,335			21%
State income taxes, net of federal tax benefit	4,333			2%	3,834			1%	7,016			3%
Tax effect of permanent differences	2,018			1%	1,860			1%	1,369			1%
Tax effect of state income tax deduction	(209)			—%	(443)			—%	(1,254)			—%
Amortization of excess deferred federal income taxes	(15,680)			(6)%	(20,565)			(8)%	(17,986)			(7)%
Amortization of excess deferred state income taxes	(10,004)			(4)%	(1,795)			(1)%	—			—%
Tax (expense) benefit for employee share-based compensation	1,063			—%	418			—%	350			—%
Other, net	426			—%	123			—%	696			—%
Total provision for income taxes and effective income tax rate	$	36,386		14%	$	40,495		14%	$	46,526		18%

Schedule of Deferred Tax Assets and Liabilities

The following table sets forth the tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and liabilities for the periods indicated:


	December 31,
	2024		2023
	(Thousands of dollars)
Deferred tax assets
Employee benefits and other accrued liabilities	$	—	$	—
Regulatory adjustments for enacted tax rate changes	100,718		107,948
Net operating loss	405,316		93,255
Lease obligation basis	3,669		4,500
Purchased-gas cost adjustment	—		5,232
Other	—		—
Total deferred tax assets	509,703		210,935
Deferred tax liabilities
Excess of tax over book depreciation	930,680		822,619
Winter weather event costs	381,818		56,914
Purchased-gas cost adjustment	8,654		—
Other regulatory assets and liabilities, net	73,904		70,384
Employee benefits and other accrued liabilities	934		205
Right-of-use asset basis	3,866		4,662
Other	1,585		8,219
Total deferred tax liabilities	1,401,441		963,003
Net deferred tax liabilities	$	891,738	$	752,068