INCOME TAXES

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The components of deferred tax assets and liabilities at December 31, 2016 and 2015, are as follows:



(in millions)	2016		2015
DEFERRED TAX LIABILITIES:
Accelerated depreciation	$	4,726	$	4,429
Other	134		62
Total deferred tax liabilities	4,860		4,491
DEFERRED TAX ASSETS:
Fuel derivative instruments	233		750
Construction obligation	402		289
Accrued employee benefits	451		541
Other	400		421
Total deferred tax assets	1,486		2,001
Net deferred tax liability	$	3,374	$	2,490

The provision for income taxes is composed of the following:



(in millions)	2016		2015			2014
CURRENT:
Federal	$	778	$	1,292		$	203
State	69		114			29
Total current	847		1,406			232
DEFERRED:
Federal	426		(97		)	421
State	30		(11		)	27
Total deferred	456		(108		)	448
	$	1,303	$	1,298		$	680

The effective tax rate on income before income taxes differed from the federal income tax statutory rate for the following reasons:



(in millions)	2016			2015		2014
Tax at statutory U.S. tax rates	$	1,241		$	1,218	$	636
State income taxes, net of federal benefit	64			66		37
Other, net	(2		)	14		7
Total income tax provision	$	1,303		$	1,298	$	680

The only periods subject to examination for the Company’s federal tax return are the 2015 and 2016 tax years.