Quarterly report pursuant to Section 13 or 15(d)


3 Months Ended
Mar. 31, 2021
Income Tax Disclosure [Abstract]  
INCOME TAXES INCOME TAXESWe file an income tax return in the U.S. federal jurisdiction and a margin tax return in Texas. Previously, the Texas Comptroller selected the R&D credit calculations related to the 2014 and 2015 calendar years for audit. The state of Texas suspended examination of the 2014 and 2015 calendar years in order to perform a comprehensive review of audit procedures to provide consistency. During the fourth quarter of 2019, we received notice that Texas had completed review of its procedures and initiated additional requests for information which has been submitted for their review. In February 2020, we received notice from the Internal Revenue Service (“IRS”) regarding the IRS's selection of the Company for an income tax
audit for the tax period ending December 31, 2017. We do not expect any material changes related to the federal or Texas audits. Our federal and Texas tax returns remain open for examination for the years 2016 through 2019. As of March 31, 2021 and December 31, 2020, respectively, we recognized no adjustments for uncertain tax positions or related interest and penalties.
The effective tax rate varies from the federal statutory rate of 21%, primarily as a result of state tax expense, stock based compensation, foreign taxes and a research and development credit for the three months ended March 31, 2021 and 2020. We continue to maintain a valuation allowance against certain deferred tax assets, specifically for mining claims for PEVM, where realization is not certain.
The CARES Act provided stimulus measures to companies impacted by the COVID-19 pandemic, which included the ability to defer payment for employer payroll taxes, utilize net operating loss (“NOL”) carrybacks, increased the limitation on the deductibility of interest expense, technical corrections to allow accelerated tax depreciation on qualified improvement property, as well as allowing qualified business to apply for loans and grants. We have filed carryback claims allowed under these provisions which are included in income tax receivable on the consolidated balance sheets.
In April 2021, we received approximately $2.5 million related to our second and final NOL carryback claims, including approximately $0.1 million of interest income.