Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Schedule of Components of Income Tax Expense (Benefit)

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


	Years Ended December 31,
	2023		2022		2021
	(Thousands of dollars)
Current income tax provision (benefit)
Federal	$	16,551	$	61,745	$	(1,568)
State	(829)		6,815		(1,565)
Total current income tax provision (benefit)	15,722		68,560		(3,133)
Deferred income tax provision (benefit)
Federal	21,905		(22,234)		37,810
State	2,868		200		5,639
Total deferred income tax provision (benefit)	24,773		(22,034)		43,449
Total provision for income taxes	$	40,495	$	46,526	$	40,316

Schedule of Effective Income Tax Rate Reconciliation

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


	Years Ended December 31,
	2023			2022			2021
	(Thousands of dollars)
Income before income taxes	$	271,727		$	268,268		$	246,750
Federal statutory income tax rate	21		%	21		%	21		%
Provision for federal income taxes	57,063			56,335			51,817
State income taxes, net of federal tax benefit	3,834			7,016			4,074
Amortization of excess deferred federal income taxes	(20,565)			(17,986)			(17,289)
Amortization of excess deferred state income taxes	(1,795)			—			—
Tax (expense) benefit for employee share-based compensation	418			350			(469)
Other, net	1,540			811			2,183
Total provision for income taxes	$	40,495		$	46,526		$	40,316

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,
	2023		2022
	(Thousands of dollars)
Deferred tax assets
Employee benefits and other accrued liabilities	$	—	$	4,256
Regulatory adjustments for enacted tax rate changes	107,948		114,551
Net operating loss	93,255		161,320
Lease obligation basis	4,500		9,158
Purchased-gas cost adjustment	5,232		3,384
Other	—		3,014
Total deferred tax assets	210,935		295,683
Deferred tax liabilities
Excess of tax over book depreciation	822,619		792,570
Winter weather event costs	56,914		121,347

Other regulatory assets and liabilities, net	70,384		71,180
Employee benefits and other accrued liabilities	205		—
Right-of-use asset basis	4,662		9,042
Other	8,219		—
Total deferred tax liabilities	963,003		994,139
Net deferred tax liabilities	$	752,068	$	698,456