We have historically provided for income taxes during interim reporting periods based on an estimate of the annual effective tax rate applied to the income for the year to date interim period. For 2020, we continue to utilize this approach.

On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) was enacted in response to the COVID-19 pandemic. The CARES Act contains numerous income tax provisions, some of which materially impact MPC's calculation of income taxes including:

We recorded an overall income tax benefit of $1.6 billion for the six months ended June 30, 2020, of which $309 million was attributable to the tax rate differential in the carryback years resulting from the expected NOL carryback provided under the CARES Act. As of June 30, 2020, the estimated cash tax refund resulting from the NOL carryback provided in the CARES Act is $1.1 billion and arises solely due to taxes paid in prior years. Absent the CARES Act, we would have recorded a deferred tax asset for the expected NOL carryforward under the currently effective federal income tax rate. For the three months ended June 30, 2020, we recorded income tax expense of $360 million, which reflects a change in our estimated annual effective tax rate and CARES Act benefit.

The combined federal, state and foreign income tax rate was 14 percent for the six months ended June 30, 2020. Our effective tax benefit rate was lower than the statutory rate primarily due to a significant amount of our pre-tax loss consisting of non-tax deductible goodwill impairment charges, partially offset by the tax rate differential resulting from the expected NOL carryback provided under the CARES Act. Additionally, our effective tax rate is generally benefited by our noncontrolling interest in MPLX, but this benefit was lower for the six months ended June 30, 2020 compared to the six months ended June 30, 2019 due to impairment charges recorded by MPLX.

The combined federal, state and foreign income tax rate was 57 percent for the three months ended June 30, 2020. The effective tax rate for the three months ended June 30, 2020 was higher than the U.S. statutory rate of 21 percent as well as higher than the effective rate for the three months ended June 30, 2019 primarily due the tax rate differential resulting from the expected NOL carryback provided under the CARES Act, permanent differences related to net income attributable to noncontrolling interests and changes in our estimated annual effective rate applied to income for the year to date interim period.

Based on the estimated NOL carryback, as provided by the CARES Act, we recorded an income tax receivable of $1.1 billion in other noncurrent assets to reflect our estimate of the tax refund we expect to realize at the time of our 2020 tax return filing, which is expected during the second half of 2021.

A reconciliation of the tax provision (benefit) in dollars as determined using the federal statutory income tax rate applied to income (loss) before income taxes to the (benefit) provision for income taxes is shown in the table below.



	Three Months Ended June 30,					Six Months Ended June 30,
(In millions)	2020		2019			2020			2019
Tax computed at statutory rate	$	133	$	361		$	(2,419	)	$	437
State and local income taxes, net of federal income tax effects	33		45			(167		)	88
Goodwill impairment	—		—			1,156			—
Noncontrolling interests	81		(68		)	150			(83		)
CARES Act legislation	102		—			(309		)	—
Other	11		15			12			15
Total provision (benefit) for income tax	$	360	$	353		$	(1,577	)	$	457

During the first quarter of 2019, MPC’s provision for income taxes was increased $36 million for an out of period adjustment to correct the tax effects recorded in 2018 related to the Andeavor acquisition. The impact of the adjustment was not material to any previous period.

We are continuously undergoing examination of our income tax returns, which have been completed through the 2005 tax year for state returns and the 2010 tax year for our U.S. federal return. As of June 30, 2020, we had $25 million of unrecognized tax benefits.

Pursuant to our tax sharing agreement with Marathon Oil, the unrecognized tax benefits related to pre-spinoff operations for which Marathon Oil was the taxpayer remain the responsibility of Marathon Oil and we have indemnified Marathon Oil accordingly. See Note 22 for indemnification information.