
	2020		2019		2018
Current:
Federal	$	4,877	$	82,484	$	136,202
State	2,614		6,421		23,134
Foreign	19,560		23,328		29,823
	27,051		112,233		189,159
Deferred:
Federal	(30,779)		18,760		(23,181)
State	(11,579)		402		(6,787)
Foreign	(1,721)		2,385		(4,013)
	(44,079)		21,547		(33,981)
	$	(17,028)	$	133,780	$	155,178

Income tax (benefit) provision differs from the amount that would be provided by applying the statutory U.S. corporate income tax rate for the years ended December 31, due to the following items (in thousands):


	2020		2019		2018
(Benefit) provision at statutory rate	$	(3,303)	$	117,057	$	144,192
State taxes, net of federal benefit	822		14,165		18,086
Foreign rate differential	60		1,665		2,712

Foreign derived intangible income	—		(3,108)		(8,400)
Research and development credit	(8,442)		(8,200)		(7,400)
Unrecognized tax benefits including interest and penalties	(8,567)		289		(4,121)
Valuation allowance adjustments	9,675		8,070		908
State credits	(13,106)		(4,704)		—

Deferred tax balance remeasurement for rate change	—		—		(8,098)
Territorial tax	—		—		9,556
Global intangible low-taxed income	1,480		1,113		2,437
Adjustments for previously accrued taxes	(4,951)		(1,755)		(7,196)
Rate differential on intercompany transfers	—		—		6,013
Executive compensation limitation	2,543		2,620		3,171
Other foreign inclusions	4,415		4,202		1,787
Other	2,346		2,366		1,531
Income tax (benefit) provision	$	(17,028)	$	133,780	$	155,178

The 2017 Tax Cuts and Jobs Act subjects U.S. shareholders to current tax on global intangible low-taxed income (GILTI) earned by certain foreign subsidiaries for which a company can elect to either recognize deferred taxes or to provide tax expense in the year incurred. The Company has elected to account for GILTI in the year the tax is incurred.


	2020		2019
Deferred income tax assets:
Accruals not yet tax deductible	$	142,100	$	95,746
Pension and postretirement healthcare plan obligations	6,499		17,685
Stock compensation	9,619		11,867
Net operating loss and credit carryforwards	55,857		45,279
Valuation allowance	(38,072)		(29,024)
Other	78,051		64,833
	254,054		206,386
Deferred income tax liabilities:
Depreciation, tax in excess of book	(74,579)		(83,477)
Other	(29,544)		(29,840)
	(104,123)		(113,317)
	$	149,931	$	93,069

The Company reviews its deferred income tax asset valuation allowances on a quarterly basis, or whenever events or changes in circumstances indicate that a review is required. In determining the requirement for a valuation allowance, the historical and projected financial results of the legal entity or consolidated group recording the net deferred income tax asset is considered, along with any positive or negative evidence including tax law changes. Since future financial results and tax law may differ from previous estimates, periodic adjustments to the Company’s valuation allowances may be necessary.

At December 31, 2020, the Company had a deferred tax asset of $45.9 million related to its state operating loss and Wisconsin research and development credit carryforwards and a deferred tax asset of $10.0 million related to foreign net operating losses.

The Company's valuation allowance was $38.1 million at December 31, 2020 and included $17.7 million related to state operating loss and Wisconsin research and development credit carryforwards, $6.5 million related to foreign net operating losses and $13.9 million related to other deferred tax assets. The increase in the valuation allowance from prior year included $8.0 million related to state operating loss and Wisconsin research and development credit carryforwards and $1.0 million related to foreign net operating losses.

The Company recognizes interest and penalties related to unrecognized tax benefits in Income tax (benefit) provision. Changes in the Company’s gross liability for unrecognized tax benefits, excluding interest and penalties, were as follows (in thousands):


	2020		2019
Unrecognized tax benefits, beginning of period	$	60,112	$	61,411
Increase in unrecognized tax benefits for tax positions taken in a prior period	1,649		1,067
Decrease in unrecognized tax benefits for tax positions taken in a prior period	(12,560)		(5,608)
Increase in unrecognized tax benefits for tax positions taken in the current period	3,092		4,576
Statute lapses	—		(325)
Settlements with taxing authorities	(1,696)		(1,009)
Unrecognized tax benefits, end of period	$	50,597	$	60,112

The amount of unrecognized tax benefits as of December 31, 2020 and 2019 that, if recognized, would affect the effective tax rate was $43.8 million and $53.1 million, respectively.

The total gross amount of benefit related to interest and penalties associated with unrecognized tax benefits recognized during 2020, 2019 and 2018 in the Consolidated statements of operations was $2.1 million, $0.1 million and $3.2 million, respectively.

The total gross amount of interest and penalties associated with unrecognized tax benefits recognized at December 31, 2020 and 2019 in the Consolidated balance sheets was $25.5 million and $27.6 million, respectively.

The Company does not expect a significant increase or decrease to the total amounts of unrecognized tax benefits related to continuing operations during the fiscal year ending December 31, 2021. However, the Company is under regular audit by tax authorities. The Company believes that it has appropriate support for the positions taken on its tax returns and that its annual tax provision includes amounts sufficient to pay any assessments. Nonetheless, the amounts ultimately paid, if any, upon resolution of the issues raised by the taxing authorities may differ materially from the amounts accrued for each year.

The Company or one of its subsidiaries files income tax returns in the U.S. federal and Wisconsin state jurisdictions and various other state and foreign jurisdictions. The Company is no longer subject to income tax examinations for Wisconsin state income taxes before 2016 or for U.S. federal income taxes before 2017.