(7) Income Taxes

All taxes presented prior to March 7, 2014 relate to the predecessor’s results of continuing operations. Taxes presented for the periods subsequent to March 6, 2014 relate to the combined operations of ENLC, Predecessor and the remaining underlying operating entities.

The components of the provision for income tax expense are as follows (in millions):


	Year Ended December 31,
	2016		2015		2014
Current income tax expense	$	2.5	$	3.1	$	9.0
Deferred tax expense		2.1		22.6		67.4
Total income tax expense	$	4.6	$	25.7	$	76.4

The statutory federal income tax rate applied to pre-tax book income reconciles to income tax expense as follows in millions):


	Year Ended December 31,
	2016		2015		2014
Expected income tax expense (benefit) based on federal statutory rate of 35%	$	(159.4)	$	(116.0)	$	70.7
State income taxes, net of federal benefit and other		(9.8)		(7.7)		5.7
Goodwill impairment		173.8		149.4		—
Total income tax expense	$	4.6	$	25.7	$	76.4

Deferred Tax Assets and Liabilities

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. Our deferred income tax assets and liabilities as of December 31, 2016 and 2015 are as follows (in millions):


	Year Ended December 31,
	2016		2015
Deferred income tax assets:
Asset retirement obligations and other	$	0.9	$	2.3
State net operating loss carryforward		6.5		3.6
Federal net operating loss carryforward		59.5		20.9
Total deferred tax assets		66.9		26.8
Deferred tax liabilities:
Property, plant, equipment, and intangible assets		(609.5)		(557.6)
Other		—		(1.3)
Total deferred tax liabilities		(609.5)		(558.9)
Deferred tax liability, net	$	(542.6)	$	(532.1)

(1)

Includes our investment in the Partnership, and primarily relates to differences between the book and tax bases of property, plant and equipment.

As of December 31, 2016, we had federal net operating loss carryforwards of $170.1 million that represent a net deferred tax asset of $59.5 million. As of December 31, 2016, we had state net operating loss carryforwards of $123.0 million that represent a net deferred tax asset of $6.5 million. These carryforwards will begin expiring in 2028 through 2036. Management believes that it is more likely than not that the future results of operations will generate sufficient taxable income to utilize these net operating loss carryforwards before they expire.

A reconciliation of the beginning and ending amounts of unrecognized tax benefits is as follows (in millions):


	Year Ended December 31,
	2016		2015		2014
Beginning balance, January 1	$	1.5	$	2.0	$	—
Unrecognized tax positions assumed in merger		—		—		3.8
Decrease due to prior year tax positions		(1.5)		(0.5)		(2.0)
Increases due to current year tax positions		—		—		0.2
Ending balance, December 31	$	—	$	1.5	$	2.0

There were no unrecognized tax benefits as of December 31, 2016.

Per our accounting policy election, penalties and interest related to unrecognized tax benefits are recorded to income tax expense. As of December 31, 2016, tax years 2012 through 2016 remain subject to examination by various taxing authorities.