Conor Clarke (WashU) & Noah Marks (UNC), Tax Exceptionalism After Loper Bright, 192 Tax Notes Fed. 1963 (2026)

We consider how tax regulations should be reviewed in a post-Chevron world. In 2011, the Supreme Court’s Mayo Foundation decision subjected Treasury regulations to ordinary Chevron deference, rejecting National Muffler’s tax-specific standard of review and declaring that the Court was “not inclined to carve out an approach to administrative review good for tax law only.” In 2024, Loper Bright overruled Chevron. This Article asks what Loper Bright means for Mayo—and, in turn, for National Muffler. 

We reject the simple inference that Loper Bright automatically revives National Muffler. But we argue that National Muffler nonetheless has a strong claim to renewed relevance: its reasoning substantially overlaps with Skidmore—and, more broadly, with Loper Bright’s delegation-specific methodology. We also explore two further implications suggested by our analysis. First, Loper Bright’s approach may invite a wider return of agency-specific deference in tax law and elsewhere. Second, National Muffler offers an entry point into a little-examined body of pre-Administrative Procedure Act caselaw reviewing Treasury regulations. This caselaw gives courts and practitioners a largely untapped resource for the kind of inquiry that Loper Bright now requires.