8. Income Taxes

The effective tax rate differs from the statutory tax rate as follows:



	Three months ended March 31,
	2018		2017
Statutory U.S. federal income tax rate	21.0	%	35.0	%
State income tax, net of related federal income tax benefit	5.6		4.0
Foreign operations	0.6		0.7
Federal credits	(1.2)		(1.0)
Executive compensation disallowed	1.6		-
Meals and entertainment	1.3		-
Other	(0.1)		0.3
Discrete items	8.1		(1.0)
Effective income tax rate	36.9	%	38.0	%

The 2017 Tax Cuts and Jobs Act (the "TCJA") reduced the U.S. corporate tax rate from 35% to 21% for tax years beginning after December 31, 2017. The reduction is offset by an increase in the effective state tax rate due to the impact of state tax deductions at the lower federal tax rate, and the impact of non-deductible items that were added or expanded by the TCJA. The tax rate is further impacted during the three months ended March 31, 2018 by excess tax deficits on stock-based compensation.

In 2017, we recorded a tax benefit of $6,047 which we believed was the impact of the enactment of the TCJA. The benefit was based on currently available information and interpretations, which are continuing to evolve, and as a result, the benefit is considered provisional. We continue our analysis related to the TCJA as supplemental legislation, regulatory guidance, or evolving technical interpretations become available. Based on supplemental legislation issued during 2018, we recorded additional tax expense of $399. We will continue to refine such amounts within the measurement period as provided by Staff Accounting Bulletin Number 118. We expect to complete our analysis no later than the fourth quarter of 2018.