Shawn O’Brien

Shawn O’Brien is nationally recognized by his peers and clients as a leading tax practitioner with a focus on tax disputes and controversies involving state, federal and international tax authorities. Drawing on his 25 years of experience, Shawn represents clients in tax examinations and administrative appeals and, when necessary, serves as a forceful advocate in litigation before the US Tax Court, US district courts, the US Court of Federal Claims, state courts and federal appellate courts. Read Shawn O’Brien's full bio.
The Employee Retention Credit: A court challenge to IRS guidance
By Shawn O’Brien, Samuel F. Hamer and Michael J. Scarduzio on Jul 8, 2025
Posted In Court Procedure Matters, IRS Guidance, Trial Courts
Case: Stenson Tamaddon LLC v. IRS, No. CV-24-01123-PHX-SPL, 2025 WL 1725942 (D. Ariz. June 20, 2025) On June 20, 2025, the US District Court for the District of Arizona denied a motion for summary judgment that was filed by Stenson Tamaddon LLC (StenTam). The tax advisory firm argued that IRS Notice 2021-20, which provided informal guidance...
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Potential Refund Opportunity for Interest and Penalty Amounts Accrued During COVID-19 Federally Declared Disaster
By Shawn O’Brien and Samuel F. Hamer on Jun 12, 2025
Posted In IRS Appeals, IRS Audits, Settlements, Tax Refunds, Trial Courts
Taxpayers who made payments to the Internal Revenue Service (IRS) that included underpayment interest and/or failure-to-file/pay penalties that accrued during all or part of the period between January 20, 2020, through July 10, 2023, should consider filing a refund claim with the IRS to potentially recover accrued interest and penalty amounts. Internal Revenue Code (IRC)...
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“Big, Beautiful Bill”: Federal Tax Bill Would Restrict the Employee Retention Credit
By Shawn O’Brien, Samuel F. Hamer and Michael J. Scarduzio on May 20, 2025
Posted In Tax Reform
A sweeping federal tax bill that is currently under consideration in the US House of Representatives contains provisions that would significantly change the administration and enforcement of the Employee Retention Credit (ERC). The ERC was enacted in 2020 as part of the Coronavirus Aid, Relief, and Economic Security (CARES) Act to provide financial relief to...
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The Employee Retention Credit: IRS’s “Risking” Model Faces Legal Challenge
By Shawn O’Brien, Samuel F. Hamer and Michael J. Scarduzio on Apr 24, 2025
Posted In Court Procedure Matters, IRS Appeals, Trial Courts
Case: ERC Today LLC et al. v. John McInelly et al., No. 2:24-cv-03178 (D. Ariz.) In an April 2025 order, the US District Court for the District of Arizona denied a motion for a preliminary injunction filed by two tax preparation firms. The firms sought to halt the Internal Revenue Service’s (IRS) use of an...
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The Employee Retention Credit: How to Litigate and Resolve Claims
By Shawn O’Brien, Michael J. Scarduzio and Samuel F. Hamer on Apr 10, 2025
Posted In IRS Appeals
The Employee Retention Credit (ERC) was designed to help employers keep their employees on payroll during the COVID-19 pandemic by offering a refundable tax credit against certain employment taxes. Despite the Internal Revenue Service (IRS) issuing more than $242 billion in ERC as of early 2025, the processing and payment of these claims have faced...
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Upcoming Webinar: Navigating IRS Tax Refunds
By Shawn O’Brien, Susan E. Ryba and Samuel F. Hamer on Mar 31, 2025
Posted In Tax Refunds
On April 9, 2025, join McDermott’s Tax Controversy & Litigation Group for an insightful webinar on the intricacies of claiming and collecting Internal Revenue Service (IRS) tax refunds. This session is designed for tax professionals, legal practitioners, and anyone interested in understanding the complexities of the IRS refund claims process and what to watch out...
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Upcoming Webinar: Defeating IRS Penalties
By Edward L. Froelich, Shawn O’Brien and Michael J. Scarduzio on Feb 25, 2025
Posted In Court Procedure Matters, IRS Audits
The IRS has an extensive set of penalties that it can impose on both corporate and individual taxpayers, and recent audit trends indicate a growing tendency to apply multiple penalties. Join McDermott’s Tax Controversy & Litigation Group on March 5, 2025, for a webinar that will dive into the penalties the IRS may pursue and...
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IRS Announces New Compliance Initiatives to Collect More Corporate Tax Using Inflation Reduction Act Funds
By Kevin Spencer, Edward L. Froelich and Shawn O’Brien on Oct 24, 2023
Posted In IRS Audits, IRS Guidance
On October 20, 2023, the Internal Revenue Service (IRS) announced new initiatives “to ensure large corporations pay taxes owed.” These initiatives leverage the substantial additional congressional funding that was given to the IRS thanks to the Inflation Reduction Act of 2022 (IRA). (We previously reported on how IRS enforcement is impacted by IRA funding here.)...
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