The components of income tax expense for the years ended December 31 are as follows:

	2019			2018			2017
Current income tax expense (benefit):
Federal	$	1,339		$	585		$	(15,424	)
State		2,625			(51	)		1,162
Total current tax expense (benefit)		3,964			534			(14,262	)
Deferred income tax expense (benefit):
Federal		3,031			(7,868	)		8,389
State		(1,564	)		1,932			3,628
Total deferred tax expense (benefit)		1,467			(5,936	)		12,017
Income tax expense (benefit), as reported	$	5,431		$	(5,402	)	$	(2,245	)

Reported income tax expense (benefit) differed from the amounts computed by applying the U.S. federal statutory income tax rate of 21% in 2019 and 2018 and 35% in 2017 to income before income taxes as follows:

	2019			2018			2017
Income tax expense computed at the statutory rate	$	4,928		$	9,670		$	34,389

State income tax, net of federal benefit		838			1,485			3,114
Stock-based compensation expense		443			268			(380	)
Change in U.S. tax rate		—			244			(18,921	)
Decrease in taxes due to investment tax credit		(1,561	)		(17,846	)		(20,509	)
Other		783			777			62
Total income tax expense (benefit)	$	5,431		$	(5,402	)	$	(2,245	)

On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cut and Jobs Act (the “Tax Act”). The Tax Act made broad and complex changes to the U.S. tax code that affected 2018 and 2017, including, but not limited to, accelerated depreciation that allows for full expensing of qualified property. The Tax Act also enacted a reduction in the U.S. federal corporate income tax rate from 35% to 21% which became effective in 2018. The 21% tax rate positively impacted 2017 due to the revaluation of the Company’s deferred tax assets and liabilities. As such, the Company recorded a provisional net tax benefit of $18.9 million in 2017.

On December 22, 2017, the SEC staff issued Staff Accounting Bulletin No. 118 (“SAB 118”), which provided guidance on accounting for the tax effects of the Tax Act. SAB 118 provided a measurement period that could not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740, Income Taxes. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Tax Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. During the measurement period, a company must record adjustments to its provisional estimate upon obtaining, preparing, or analyzing additional information about facts and circumstances that existed as of the enactment date that, if known, would have affected the provisional estimate. As noted above, the Company recorded a provisional net tax benefit of $18.9 million in its 2017 consolidated financial statements. Upon completing the accounting for the effects of the Tax Act, the Company recorded $244 thousand of additional income tax expense during 2018.

	2019		2018
Deferred tax assets:
Tax credit carryforwards	$	37,619	$	39,560
Allowance for loan and lease losses		11,579		7,784
Net operating loss carryforwards		83		5,046
Mark to market on loans held for sale		10,501		1,780
Stock-based compensation expense		4,918		3,004
Goodwill and intangibles		720		720
Accrued expenses		1,372		430
Net unrealized losses on securities available for sale		—		529
Operating lease liabilities		629		—
Other		977		1,573
Total deferred tax assets		68,398		60,426

Deferred tax liabilities:
Investment in joint venture		15,538		16,596
Unguaranteed loan discount		13,076		8,535
Premises and equipment		45,291		40,032
Deferred loan fees and costs, net		1,417		987
Net unrealized gains on securities available for sale		3,702		—
Operating lease right-of-use assets		584		—
Other		538		326
Total deferred tax liabilities		80,146		66,476
Net deferred tax liability	$	11,748	$	6,050

The Company has recorded a deferred tax asset of $37.6 million related to federal tax credit carryforwards which will begin to expire in 2037.

Management assesses the realizability of deferred tax assets at each reporting period and considers whether it is more likely than not that a deferred tax asset will not be realized. The realization of a deferred tax asset is dependent upon the generation of future taxable income during periods in which the related temporary difference becomes deductible or realizable prior to its expiration. Management considers projected future taxable income, scheduled reversal of deferred tax liabilities, cessation of investing in renewable energy assets that generate investment tax credits and tax planning strategies in making this assessment. Based on these considerations, management believes it is more likely than not that the deferred tax assets will be realized.

The Company does not have any material uncertain tax positions and does not have any interest and penalties recorded in the income statement for the years ended December 31, 2019, 2018 and 2017. The Company files a consolidated income tax return in the U.S. federal tax jurisdiction.

Generally, the Company’s federal and state tax returns are no longer subject to examination by the taxing authorities for years prior to 2015.