1. Requirements for PDP sponsors of prescription drug plans under part D of the Medicare program that use formularies (a) In general Section 1860D–4(b)(3) of the Social Security Act ( 42 U.S.C. 1395w–104(b)(3) ) is amended by adding at the end the following new subparagraphs: (I) Required inclusion of certain generic drugs and biosimilar biological products (i) In general With respect to a plan year beginning on or after January 1, 2021, the formulary shall include— (I) each covered generic drug for which the wholesale acquisition cost is less than the wholesale acquisition cost of the reference drug of such covered generic drug