We record current income tax expense for the amounts that we expect to report and pay on our income tax returns and deferred income tax expense for the change in the deferred tax assets and liabilities. On December 22, 2017, the U.S. enacted the Tax Cuts and Jobs Act (the “Tax Act”) that significantly changed U.S. tax law. One part of this Tax Act required the Company to pay a deemed repatriation tax of $5.2 million on its cumulative foreign E&P. After application of tax payments and credits, $1.0 million of the liability remains outstanding as of December 31, 2020 and is due in 2024.

Income from continuing operations before income taxes consisted of the following:

Significant components of the income tax provision from continuing operations are as follows:

	Year Ended December 31,
(in thousands)	2020			2019			2018
Current:
United States:
Federal	$	(128	)	$	(2,260	)	$	41
State		674			1,400			(335	)
Foreign		(1,397	)		13,764			12,039
Total current		(851	)		12,904			11,745
Deferred:
United States:
Federal		17,171			(3,355	)		1,860
State		2,896			(1,619	)		860
Foreign		(4,970	)		(5,424	)		2,630
Total deferred		15,097			(10,398	)		5,350
Income tax expense	$	14,246		$	2,506		$	17,095

We are subject to income tax in jurisdictions in which we operate. A reconciliation of the statutory federal income tax rate to the effective tax rate is as follows:

	Year Ended December 31,
(in thousands)	2020					2019					2018
Computed income tax (benefit) expense at statutory federal income tax rate	$	(75,780	)	21.0	%	$	5,483		21.0	%	$	13,665		21.0	%
State income tax (benefit), net of federal benefit		(4,138	)	1.1	%		(173	)	(0.2	)%		3,489		5.4	%
Deemed mandatory repatriation state tax		—		0.0	%		—		0.0	%		(909	)	(1.4	)%
Deemed mandatory repatriation federal tax, net of foreign tax credit		—		0.0	%		—		0.0	%		(1,690	)	(2.6	)%
Remeasurement of deferred taxes due to change in tax rates		—		0.0	%		(4,517	)	(17.3	)%		(510	)	(0.8	)%
Foreign tax rate differential		(401	)	0.1	%		3,122		12.0	%		4,138		6.4	%
U.S. tax (benefit) on current year foreign earnings, net of foreign tax credits		—		0.0	%		(1,792	)	(6.9	)%		(223	)	(0.3	)%
Goodwill impairment		16,471		(4.6	)%		—		0.0	%		—		0.0	%
Change in valuation allowance		77,369		(21.3	)%		920		1.8	%		(653	)	(1.0	)%
Other adjustments, net		725		(0.2	)%		(537	)	(0.8	)%		(212	)	(0.3	)%
Income tax expense	$	14,246		(3.9	)%	$	2,506		9.6	%	$	17,095		26.4	%

The components of deferred income tax assets and liabilities included in the Consolidated Balance Sheets are as follows:

	December 31,
(in thousands)	2020			2019
Deferred tax assets:
Tax credit carryforwards	$	5,326		$	7,879
Pension, compensation, and other employee benefits		11,991			17,231
Provisions for losses		4,623			4,778
Net operating loss carryforwards		44,358			5,371
State income taxes		—			3,089
Leases		660			—
Goodwill and other intangible assets		18,055			—
Other deferred income tax assets		14,175			2,177
Total deferred tax assets		99,188			40,525
Valuation allowance		(81,795	)		(4,276	)
Foreign deferred tax assets included above		(7,717	)		(2,351	)
United States net deferred tax assets		9,676			33,898
Deferred tax liabilities:
Property and equipment		(24,017	)		(20,681	)
Goodwill and other intangible assets		(8,846	)		(16,172	)
Leases		(857	)		—
Life insurance		—			(3,945	)
Other deferred income tax liabilities		(4,485	)		(1,858	)
Total deferred tax liabilities		(38,205	)		(42,656	)
Foreign deferred tax liabilities included above		28,490			31,192
United States net deferred tax assets (liabilities)	$	(39	)	$	22,434

We use significant judgment in forming conclusions regarding the recoverability of our deferred tax assets and evaluate all available positive and negative evidence to determine if it is more-likely-than-not that the deferred tax assets will be realized. To the extent recovery does not appear likely, a valuation allowance must be recorded. In determining the recoverability of our deferred assets, we considered our cumulative loss incurred over the four-year period ended December 31, 2020 in each tax jurisdiction. Given the weight of objectively verifiable historical losses from our operations, we recorded a valuation allowance on all deferred tax assets in the U.S., United Kingdom, Germany, and Switzerland. We had gross deferred tax assets of $99.2 million as of December 31, 2020 and $40.5 million as of December 31, 2019.

The valuation allowance was $81.8 million at December 31, 2020 and $4.3 million at December 31, 2019. The increase was primarily due to an increase for net operating losses, credit carryforwards, and deferred tax assets that do not meet the more likely-than-not threshold for recognition.

As of December 31, 2020, foreign tax credit carryforwards were $4.5 million, of which $3.8 million are foreign tax credits against U.S. income tax, which will begin to expire in 2022 and $0.7 million are creditable against United Kingdom taxes, which can be carried forward indefinitely. As of December 31, 2020, we had $0.7 million of U.S. research and development credit carryforwards.

We had gross federal, state, and foreign net operating loss carryforwards of $371.2 million as of December 31, 2020 and $55.2 million as of December 31, 2019, for which we had deferred tax assets of $44.4 million as of December 31, 2020 and $5.4 million as of December 31, 2019. Certain state net operating loss carryforwards of $181.5 million expire from 2020 through 2039, although many states now have unlimited carryforwards. We recorded a valuation allowance on all net operating losses except losses generated in Canada, the Netherlands, Iceland, and Poland. The Canadian net operating loss carryforwards of $28.4 million may be carried back three years and carried forward 20 years. The net operating losses of Iceland and Poland of $8.8 million will expire between five and ten years. The remaining amount of foreign net operating losses of $25.6 million may be carried forward indefinitely.

We have not recorded deferred taxes for withholding taxes on current unremitted earnings of our subsidiaries located in Canada, the United Kingdom, and the Netherlands as we expect to reinvest those earnings in operations outside of the U.S.

We exercise judgment in determining the income tax provision for positions taken on prior returns when the ultimate tax determination is uncertain. We classify liabilities associated with uncertain tax positions as “Other deferred items and liabilities” in the Consolidated Balance Sheets unless expected to be paid or released within one year. We had liabilities associated with uncertain tax positions of $0.3 million as of December 31, 2020 and $0.2 million as of December 31, 2019. As of December 31, 2020, these amounts do not include any accrual of interest nor penalties as none would be owed on these amounts. We elected that all uncertain tax positions, including interest and penalties, are classified as a component of income tax expense.

A reconciliation of the liabilities associated with uncertain tax positions (excluding interest and penalties) is as follows:

(in thousands)
Balance at December 31, 2017	$	1,425
Additions for tax positions taken in prior years		31
Reductions for lapse of applicable statutes		(1,086	)
Balance at December 31, 2018		370
Additions for tax positions taken in prior years		151
Reductions for lapse of applicable statutes		(296	)
Balance at December 31, 2019		225
Additions for tax positions taken in prior years		25
Reductions for lapse of applicable statutes		—
Balance at December 31, 2020	$	250

Our 2017 through 2019 U.S. federal tax years and various state tax years from 2015 through 2019 remain subject to income tax examinations by tax authorities. The tax years 2016 through 2019 remain subject to examination by various foreign taxing jurisdictions.

We received cash refunds from income taxes of $14.9 million during 2020 and paid cash for income taxes of $17.2 million during 2019 and $27.3 million during 2018.