On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act ("CARES Act") was enacted into law. The primary impact to the Company’s financial statements as a result of the CARES Act was the deferral of US corporate income tax payments from the second quarter of 2020 to July 2020, as well as the deferral of employer related payroll tax payments from the second, third and fourth quarters of 2020 with 50% to be paid in the fourth quarter of 2021 and the remaining 50% to be paid in the fourth quarter of 2022.


	Year Ended December 31,
	2020		2019		2018
Current:
Federal	$	166.5	$	224.7	$	192.6
State	49.2		56.1		43.3
Foreign	18.3		20.0		17.7
Total current	234.0		300.8		253.6
Deferred:
Domestic	(18.8)		(83.0)		(52.7)
Foreign	(1.4)		(4.9)		(3.4)
Total deferred	(20.2)		(87.9)		(56.1)
Income tax expense	$	213.8	$	212.9	$	197.5

The reconciliation between the statutory tax rate expressed as a percentage of income before income taxes and the effective tax rate was as follows:


	Year Ended December 31,
	2020				2019				2018
Statutory federal income tax rate	$	210.5	21.0	%	$	199.4	21.0	%	$	176.5	21.0	%
State taxes, net of federal effect	36.0		3.6		35.4		3.7		31.1		3.7
Excess tax benefit of equity awards	(28.8)		(2.9)		(26.8)		(2.8)		(19.7)		(2.3)
Effect of rates different than statutory	(0.8)		(0.1)		0.8		0.1		0.6		0.1
Tax on foreign earnings	1.0		0.1		2.1		0.2		2.8		0.3
Effect of tax law changes	(6.8)		(0.7)		—		—		(1.9)		(0.2)
Other	2.7		0.3		2.0		0.2		8.1		0.9
Effective tax rate	$	213.8	21.3	%	$	212.9	22.4	%	$	197.5	23.5	%

The tax effect of temporary differences that give rise to net deferred income tax liabilities is presented below. Reclassifications have been made to conform to current year presentation.


	December 31,
	2020		2019
Deferred tax assets:
Contract liabilities	$	13.2	$	46.3
Equity compensation plans	20.1		21.1
Net operating loss and credit carryforwards, net	22.9		20.1
Payroll and benefits	21.8		9.6
Operating lease liabilities	47.5		41.0
Accounts receivable	26.0		15.6
Other	15.9		14.1
Total deferred tax assets	167.4		167.8

Deferred tax liabilities:
Acquisition-related intangibles	76.5		112.2
Property and equipment	39.9		27.0
International investments	19.2		19.2
Operating lease right-of-use assets	32.5		33.7
Other	23.3		17.5
Total deferred tax liabilities	191.4		209.6
Deferred tax asset valuation allowance	16.9		16.8
Net deferred tax liabilities	$	40.9	$	58.6

The Company has international income tax net operating losses of $6 million that do not expire and state and international tax credit carryforwards of $23 million, which expire at various dates from 2024 through 2027.

Due to the nature of the CDW UK acquisition, the Company has provided US income taxes of $19 million on the excess of the financial reporting value of the investment over the corresponding tax basis. The Company is indefinitely reinvested in its UK business, and therefore will not provide for any US deferred taxes on the earnings of the UK business. The Company is not permanently reinvested in its Canadian business and therefore has recognized deferred tax liabilities of $1 million as of December 31, 2020 related to Canada withholding taxes on earnings of its Canadian business.

In the ordinary course of business, the Company is subject to review by domestic and foreign taxing authorities, including the Internal Revenue Service ("IRS"). In general, the Company is no longer subject to audit by the IRS or state, local, or foreign taxing authorities for tax years through 2014. Various taxing authorities are in the process of auditing income tax returns of the Company and its subsidiaries. The Company does not anticipate that any adjustments from the audits would have a material impact on its Consolidated Financial Statements.


	Year Ended December 31,
	2020		2019		2018

Balance as of January 1	$	17.7	$	15.1	$	—
Additions for tax positions related to current year	0.1		2.6		15.1
Additions for tax positions related to prior year	0.5		—		—


Balance as of December 31	$	18.3	$	17.7	$	15.1

As of December 31, 2020, the Company had $18 million of unrecognized tax benefits that, if recognized, would have decreased income taxes and the corresponding effective income tax rate and increased net income. The impact of