Income Tax

The components of income tax expense are as follows:



	Years Ended December 31,
	2015		2014		2013
	(in thousands)
Current tax expense	$	36,426	$	21,565	$	21,581
Deferred tax expense	6,367		14,646		5,413
Total	$	42,793	$	36,211	$	26,994

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



	December 31,
	2015			2014
	(in thousands)
Deferred tax assets:
Allowance for loan and lease losses	$	26,024		$	26,341
Supplemental executive retirement plan	10,770			9,037
Stock option and restricted stock	1,423			1,177
OREO	813			1,101
Nonaccrual interest	69			68
Purchase accounting	9,457			15,272
Unrealized loss on investment securities	3,916			—
Net operating losses and credit carryforwards	11,467			14,929
Other	180			532
Total deferred tax assets	64,119			68,457
Deferred tax liabilities:
Asset purchase tax basis difference	(9,058		)	(6,595		)
FHLB stock dividends	(1,232		)	(4,086		)
Deferred loan fees	(5,202		)	(4,691		)
Unrealized gain on investment securities	—			(2,987		)
Depreciation	(3,730		)	(5,394		)
Total deferred tax liabilities	(19,222		)	(23,753		)
Net deferred tax asset	$	44,897		$	44,704

A reconciliation of the Company’s effective income tax rate with the federal statutory tax rate is as follows:



	Years Ended December 31,
	2015					2014					2013
	Amount			Percent		Amount			Percent		Amount			Percent
	(dollars in thousands)
Income tax based on statutory rate	$	49,567		35	%	$	41,225		35	%	$	30,454		35	%
Reduction resulting from:
Tax exempt instruments	(6,761		)	(5	)%	(5,328		)	(5	)%	(4,113		)	(5	)%
Life insurance proceeds	(1,554		)	(1	)%	(1,352		)	(1	)%	(1,250		)	(1	)%
Acquisition costs	—			—	%	448			—	%	1,362			2	%
Other, net	1,541			1	%	1,218			2	%	541			—	%
Income tax provision	$	42,793		30	%	$	36,211		31	%	$	26,994		31	%

As of December 31, 2015 and 2014, we had no unrecognized tax benefits. Our policy is to recognize interest and penalties on unrecognized tax benefits in “Provision for income taxes” in the Consolidated Statements of Income. There were no amounts related to interest and penalties recognized for the years ended December 31, 2015 and 2014. The tax years subject to examination by federal and state taxing authorities are the years ending December 31, 2015, 2014, 2013 and 2012. As a result of recent acquisitions, the Company has net operating loss carryforwards in the federal, Idaho and Oregon jurisdictions of $23.6 million, $32.7 million and $540 thousand, respectively, which begin to expire in 2024 and federal and Oregon credit carryforwards of $569 thousand and $1.5 million, respectively. Federal credit carryforwards are related to alternative minimum taxes and have no expiration while the Oregon credit carryforwards begin to expire in 2016. The amount of carryforwards that may be utilized annually is limited under Sections 382 and 383 as a result of changes in control. Management believes that these carryforwards will be used in the normal course of business, and as such, has not recorded a valuation allowance.