9. Income Taxes

The components of the provision (benefit) for income taxes for the years ended December 31, 2011 and 2010 are as follows:


	Year Ended December 31,
(Thousands of dollars)	2011		2010
Current:
Federal	$	503	$	850
State		54		220

Total current		557		1,070

Deferred:
Federal		522		(192	)
State		196		124

Total deferred		718		(68	)

Total income tax provision	$	1,275	$	1,002

The components of net deferred tax assets and liabilities are as follows:


	As of December 31,
(Thousands of dollars)	2011		2010
Current Assets:
Accrued liabilities	$	474	$	439
Allowance for doubtful accounts		148		156
Derivative contracts		723		—

Total current deferred income tax assets	$	1,345	$	595

Non-Current Assets:
Alternative minimum tax credits	$	5,873	$	5,393
Net operating loss carry-forwards		161		438
Percentage depletion carry-forwards		2,946		2,538
Derivative contracts		520		—

Total non-current assets		9,500		8,369
Non-Current Liabilities:
Basis differences relating to managed partnerships		1,989		503
Depletion and depreciation		25,425		24,311

Total non-current liabilities		27,414		24,814

Net non-current deferred income tax liabilities	$	17,914	$	16,445

The total provision for income taxes for the years ended December 31, 2011 and 2010 varies from the federal statutory tax rate as a result of the following:


	Year Ended December 31,
(Thousands of dollars)	2011			2010
Expected tax expense	$	2,069		$	1,277
State income tax, net of federal benefit		167			229
Percentage depletion		(1,242	)		(504	)
Other, net		281			—

Total income tax provision	$	1,275		$	1,002

Deferred income taxes reflect the impact of temporary differences between the amount of assets and liabilities recognized for financial reporting purposes and such amounts recognized for tax purposes. Differences relating to oil and gas properties owned through Prime Offshore are reflected under "Depletion and depreciation", while basis differences relating to the managed partnerships are reflected under "Basis differences relating to managed partnerships".

The Company is entitled to percentage depletion on certain of its wells, which is calculated without reference to the basis of the property. To the extent that such depletion exceeds a property's basis, it creates a permanent difference, which lowers the Company's effective rate. The Company's lower effective tax rate in 2011 is primarily due to larger percentage depletion deductions in excess of the Company's basis in the property.

The Company has not recorded any provision for uncertain tax positions.

During 2010, the Company filed for a refund of federal income taxes paid in 2004 and 2005 based on a 2009 federal net operating loss and received refunds of $2.27 million.