In Mayo Found. for Med. Educ. & Rsch. v.
United States, 131 S.Ct. 704 (2011), the Supreme Court of
the United States made clear that administrative law rules apply to
tax guidance like they do to other federal agency guidance.
Since Mayo, the Supreme Court and other courts have
provided further guidance—both in the tax and non-tax
contexts—regarding the proper analysis in determining the
validity of, and deference to, regulatory guidance.
Over the past decade, the number of taxpayer challenges to
guidance issued by the Internal Revenue Service (IRS), whether in
the form of regulations or subregulatory guidance (i.e.,
revenue rulings, revenue procedures, notices and announcements),
has increased significantly. These challenges have taken a variety
of forms, such as regulatory invalidity under Chevron USA, Inc. v. NRDC, 467 U.S.
837 (1984) and procedural invalidity under the Administrative
Procedure Act (APA). Some successful challenges to the validity of
IRS guidance
