
	Year Ended December 31,
	2020		2019		2018
Current
Federal	$	30,193	$	23,786	$	22,658
State	3,309		4,264		2,625
	33,502		28,050		25,283
Deferred
Federal	(10,947)		17,331		13,369
State	(2,715)		2,710		3,075

	(13,662)		20,041		16,444
	$	19,840	$	48,091	$	41,727

The reconciliation of income taxes computed at the United States federal statutory tax rates to the provision for income taxes is as follows, for the periods presented:


	Year Ended December 31,
	2020		2019		2018
Tax at U.S. statutory rate	$	21,733	$	45,294	$	39,616
Increase (decrease) in taxes resulting from:
Tax-exempt interest income	(1,431)		(1,205)		(1,433)
BOLI income	(1,182)		(1,283)		(975)
Investment tax credits	(1,494)		(1,863)		(1,863)
Amortization of investment in low-income housing tax credits	1,280		1,575		1,592
State income tax expense, net of federal benefit	469		5,509		4,502


Other items, net	465		64		288
	$	19,840	$	48,091	$	41,727


	December 31,
	2020		2019
Deferred tax assets
Allowance for credit losses	$	53,597	$	14,304
Loans	5,526		10,284
Deferred compensation	13,114		12,050

Impairment of assets	1,067		1,108
Net operating loss carryforwards	1,857		9,387
Lease liabilities under operating leases	17,732		22,686
Other	3,539		5,819


Total deferred tax assets	96,432		75,638
Deferred tax liabilities

Net unrealized gains on securities	8,434		190
Investment in partnerships	793		967

Fixed assets	3,285		2,952
Mortgage servicing rights	14,623		13,472
Junior subordinated debt	2,245		2,304
Intangibles	3,882		4,885
Lease right-of-use asset	16,833		21,727
Other	1,672		1,859
Total deferred tax liabilities	51,767		48,356
Net deferred tax assets	$	44,665	$	27,282

The effective tax rate was 19.40% and 22.30% for the year ended December 31, 2020 and 2019, respectively. The Company and its subsidiaries file a consolidated U.S. federal income tax return. The Company is currently open to audit under the statute of limitations by the Internal Revenue Service for the years ending December 31, 2017 through 2019. The Company and its subsidiaries’ state income tax returns are open to audit under the statute of limitations for the years ended December 31, 2017 through 2019.

The Company acquired federal and state net operating losses as part of its previous acquisitions, with varying expiration periods. The federal and state net operating losses acquired in the Brand acquisition were $81,288 and $55,067, respectively, all created in 2018. As part of the 2017 Tax Cuts and Jobs Act and corresponding state tax laws, the federal net operating losses and the majority of the state net operating losses created by Brand during 2018 have an indefinite carryforward period. As of

December 31, 2020, there are state net operating losses without expiration periods, related to the Brand acquisition of $24,622. The federal net operating loss related to the Brand acquisition was fully utilized during 2020. The federal and state net operating losses acquired in the Heritage Financial Group, Inc. acquisition were $18,321 and $16,849, respectively, of which $3,029 and $2,205 remain to be utilized as of December 31, 2020. These losses begin to expire in 2029 and are expected to be fully utilized. Because the benefits are expected to be fully realized, the Company recorded no valuation allowance against the net operating losses for the year ended December 31, 2020.

A reconciliation of the beginning and ending amount of unrecognized tax benefits, excluding interest, related to federal and state income tax matters as of December 31 follows below:


	2020		2019		2018
Balance at January 1	$	667	$	1,919	$	1,606
Additions based on positions related to current period	101		158		313

Reductions based on positions related to prior period	(314)		(1,410)		—

Reductions due to lapse of statute of limitations	(52)		—		—
Balance at December 31	$	402	$	667	$	1,919

If ultimately recognized, the Company does not anticipate any material increase in the effective tax rate for 2020 relative to any tax positions taken prior to January 1, 2020. The Company had accrued $18, $105 and $244 for interest and penalties related to unrecognized tax benefits as of December 31, 2020, 2019 and 2018, respectively.