(5) Income Taxes

Income tax expense for the years ended December 31 is as follows:


	2015		2014		2013
Current income tax expense	$	4,822	$	5,282	$	3,240
Deferred income tax (benefit) expense		(227)		1,273		1,793
Income tax expense	$	4,595	$	6,555	$	5,033

A reconciliation of income taxes computed at the federal statutory rate to income tax expense for the years ended December 31 is as follows:


	2015				2014				2013
			Percent of				Percent of				Percent of
			Pretax				Pretax				Pretax
	Amount		Income		Amount		Income		Amount		Income
Income taxes computed at the federal statutory rate	$	6,118	35.0	%	$	9,073	35.0	%	$	6,942	35.0	%
(Reduction) increase in taxes resulting from:
Statutory depletion in excess of cost depletion		(1,708)	(9.8)			(2,139)	(8.2)			(1,965)	(9.9)
Manufacturing deduction		(548)	(3.1)			(574)	(2.2)			(299)	(1.5)
State income taxes, net of federal income tax benefit		309	1.8			104	0.4			132	0.7
Other		424	2.4			91	0.3			223	1.1
Income tax expense	$	4,595	26.3	%	$	6,555	25.3	%	$	5,033	25.4	%

Generally, US GAAP requires deferred tax assets to be reduced by a valuation allowance if, based on the weight of available evidence, it is “more likely than not” that some portion or all of the deferred tax assets will not be realized. US GAAP requires an assessment of all available evidence, both positive and negative, to determine the amount of any required valuation allowance.

Components of the Company’s deferred tax liabilities and assets are as follows:


	December 31,		December 31,
	2015		2014
Deferred tax liabilities
Lime and limestone property, plant and equipment	$	18,833	$	20,089
Natural gas interests drilling costs and equipment		3,101		3,387
Other		—		292
		21,934		23,768
Deferred tax assets
Alternative minimum tax credit carry forwards		2,259		3,887
Minimum pension liability		—		346
Fair value liability of interest rate hedges		—		240
Other		491		470
		2,750		4,943
Deferred tax liabilities, net	$	19,184	$	18,825

Current income taxes are classified on the Company’s Consolidated Balance Sheets as follows:


Prepaid expenses and other current assets		$	286		$	881

The Company had no federal net operating loss carry forwards at December 31, 2015. At December 31, 2015, the Company had determined that, because of its recent income history and expectations of income in the future, its deferred tax assets were fully realizable. The Company’s federal income tax returns for the year ended December 31, 2012 and subsequent years remain subject to examination. The Company’s income tax returns in certain state income tax jurisdictions remain subject to examination for various periods for the year ended December 31, 2012 and subsequent years. The Company treats interest and penalties on income tax liabilities as income tax expense.