(5) Income Taxes

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

	2012		2011		2010

Current income tax expense	$	3,547	$	4,398	$	3,945
Deferred income tax expense		2,131		3,560		3,073

Income tax expense	$	5,678	$	7,958	$	7,018

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

	2012						2011						2010

	Amount			Percent of pretax income			Amount			Percent of pretax income			Amount			Percent of pretax income
Income taxes computed at the federal statutory rate	$	7,735			35.0	%	$	10,550			35.0	%	$	8,770			35.0	%
(Reduction) increase in taxes resulting from:
Statutory depletion in excess of cost depletion		(2,048	)		(9.3	)		(2,366	)		(7.9	)		(1,584	)		(6.3	)
Manufacturing deduction		(335	)		(1.5	)		(308	)		(1.0	)		(397	)		(1.6	)
State income taxes, net of federal income tax benefit		331			1.5			24			0.1			155			0.6
Other		(5	)		0.0			58			0.2			74			0.3

Income tax expense	$	5,678			25.7	%	$	7,958			26.4	%	$	7,018			28.0	%

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, 2012		December 31, 2011

Deferred tax liabilities
Lime and limestone property, plant and equipment	$	19,306	$	17,625
Natural gas interests drilling costs and equipment		3,952		4,247
Other		344		316

		23,602		22,188
Deferred tax assets
Alternative minimum tax credit carry forwards		6,489		7,364
Minimum pension liability		412		448
Fair value liability of interest rate hedges		956		1,268
Other		769		611

		8,626		9,691

Net deferred tax liabilities	$	14,976	$	12,497

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


Accrued expenses	$	307	$	—
Prepaid expenses and other current assets	$	—	$	241

Deferred income taxes are classified on the Company's Consolidated Balance Sheets as follows:


Prepaid expenses and other current assets	$	678	$	515
Deferred tax liabilities, net	$	15,654	$	13,012

The Company had no federal net operating loss carry forwards at December 31, 2012. At December 31, 2012, 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, 2009 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, 2009 and subsequent years. The Company treats interest and penalties on income tax liabilities as income taxes.