This regulatory action prescribes rules related to the tax imposed by 26 U.S.C. 5000D. Section 5000D(a) imposes a tax on the sale of a designated drug by the manufacturer, producer, or importer” of such drug during a day described in section 5000D(b). The section 5000D tax arises in relation to milestones of a prescription drug price negotiation program administered by the Centers for Medicare and Medicaid Services (CMS) (the Program). See sections 119198 of the Social Security Act (SSA). Under the Program, CMS selects a small number of single-source drugs for price negotiation, SSA section 1192(a); authorized generics (meaning, roughly, drugs made under licensing agreements) are treated as single-source drugs, SSA section 1192(e)(2)(A).