	2019			2018			2017
Current:
Federal	$	(235	)	$	5,641		$	2,124
State		(151	)		1,777			1,347
Foreign		2,956			2,121			570
Deferred:
Federal		2,867			650			160
State		1,548			(365	)		242
Foreign		(1,783	)		(679	)		—
	$	5,202		$	9,145		$	4,443

Total income tax expense differed from the amounts computed by applying the U.S. Federal income tax rate of 21.0% in 2019 and 2018 and 35% in 2017 to income before income tax expense, as a result of the following:

	2019			2018			2017
Computed tax expense at statutory federal rates	$	3,993		$	7,054		$	8,651
Increase (decrease) in taxes resulting from:
State taxes, net of federal income tax benefit		1,131			1,627			988
Domestic production deduction		—			—			(150	)
Impact of the enactment of the Tax Cuts and Jobs Act (net)		—			1,089			(3,433	)
Income tax credits		(819	)		(689	)		(431	)
Foreign tax rate differential		341			(37	)		(1,503	)
Subpart F income		—			14			3
(Gain) loss on equity investments		—			(61	)		62
Stock based compensation		366			277			262
Global intangible low-taxed income		249			—			—
Other		(59	)		(129	)		(6	)
	$	5,202		$	9,145		$	4,443

	2019		2018		2017
Domestic	$	15,465	$	26,124	$	18,931
Foreign		3,547		7,472		5,922
	$	19,012	$	33,596	$	24,853

Temporary differences between the financial statement carrying amounts and tax bases of assets and liabilities that give rise to significant portions of the net deferred tax liability at December 31, 2019 and 2018 relate to the following:

	2019		2018
Deferred tax asset
Inventories	$	2,912	$	3,299
State income taxes		328		53
Program accrual		7,529		7,088
Vacation pay accrual		756		685
Accrued bonuses		599		1,246
Bad debt expense		627		294
Stock compensation		2,755		1,723
NOL carryforward		1,141		580
Tax credits		824		779
Lease liability		3,308		—
Other		209		266
Deferred tax asset	$	20,988	$	16,013
Deferred tax liability
Plant and equipment, principally due to differences in depreciation and capitalized interest	$	35,545	$	30,269
Lease asset		3,265		—
Prepaid expenses		1,323		1,107
Deferred tax liability	$	40,133	$	31,376

Total net deferred tax liability	$	19,145	$	15,363

The following is a roll-forward of the Company’s total gross unrecognized tax benefits, not including interest and penalties, for the years ended December 31, 2019 and 2018:

	2019			2018
Balance at beginning of year	$	2,170		$	2,118
Additions for tax positions related to the current year		155			128
Additions for tax positions related to the prior years		27			24
Additions for tax positions related to acquired businesses		2,458			—
Reduction for tax positions related to the prior years		(213	)		(100	)
Balance at end of year	$	4,597		$	2,170

The Company recognizes accrued interest and penalties related to unrecognized tax benefits in the provision for income taxes in the Company’s consolidated financial statements. For the years ended December 31, 2019, 2018, and 2017 the Company had recognized approximately $6,877, $2,368, and $2,257 respectively in interest and penalties related to unrecognized tax benefits.

It is expected that the amount of unrecognized tax benefits will change within the next twelve months; however, we do not expect the change to have a significant impact on our consolidated financial statements. At this time, an estimate of the range of the reasonable possible outcomes cannot be made.

The Company believes it is more likely than not that the deferred tax assets detailed in the table above will be realized in the normal course of business. It is the intent of the Company that undistributed earnings of foreign subsidiaries are permanently reinvested. The amount of undistributed earnings was $5,315 as of December 31, 2019. Upon distribution of earnings in the form of dividends or otherwise, the Company may still be subject to state income taxes and withholding taxes payable to the various foreign countries. Determination of the unrecognized deferred tax liability is not practical due to the complexities of a hypothetical calculation.

The Company is subject to U.S. federal income tax as well as to income tax in multiple state jurisdictions. Federal income tax returns of the Company are subject to IRS examination for the 2016 through 2018 tax years. State income tax returns are subject to examination for the 2015 through 2018 tax years. The Company has other foreign income tax returns subject to examination.

The Company has been notified by the Florida Department of Revenue of its intent to examine the Company’s state income tax returns for the years ended December 31, 2012 through December 31, 2013 and December 31, 2015 through December 31, 2018. The Company has also been notified by the Department of Revenue State of Mississippi of its intent to examine the Company’s state income tax returns for the years ended December 31, 2015 through December 31, 2017. Currently the results of these audits are not determinable since the audits are presently in the initial phases.

On November 9, 2018, the Company completed the purchase of all of the outstanding shares of TyraTech, Inc., a loss corporation. The Company obtained approximately $3,971 of usable federal net operating losses through the acquisition. The Internal Revenue Code of 1986, as amended, imposes restrictions on the utilization of NOLs in the event of an “ownership change” of a corporation. During 2019, the Company completed the Section 382 analysis and determined that the utilization of the losses is subject to an annual limitation of $162, with an additional $890 of net operating losses available over the first five years after the ownership change.