The IRS did not follow notice-and-comment procedures when it issued Notice 2007-83. A theme underlying a number of court decisions since the Supreme Court’s decision in Mayo Foundation is that the Administrative Procedure Act does apply to the IRS – just like it applies to every other administrative agency. The IRS appears to be slowly coming to recognize this reality, but for many, many years, the agency acted as if the APA did not apply to its actions. The Sixth Circuit’s recent decision in Mann Construction, Inc. v. United States illustrates the importance of the IRS’ prior failures in this regard, in this case in the context of listed transactions.