Section 423.180 - Basis and scope of the Part D Prescription Drug Plan Quality Rating System(a)Basis. This subpart is based on sections 1851(d), 1852(e), 1853(o) and 1854(b)(3)(iii), (v), and (vi) of the Act and the general authority under section 1856(b) of the Act requiring the establishment of standards consistent with and to carry out Part D.(b)Purpose. Ratings calculated and assigned under this subpart will be used by CMS for the following purposes:(1) To provide comparative information on plan quality and performance to beneficiaries for their use in making knowledgeable enrollment and coverage decisions in the Medicare program.(2) To provide quality ratings on a 5-star rating system.(3) To provide a means to evaluate and oversee overall and specific compliance with certain regulatory and contract requirements by Part D plans, where appropriate and possible to use data of the type described in § 423.182(c) .(c)Applicability. Except for § 423.182(b)(3) , the regulations in this subpart will be applicable beginning with the 2019 measurement period and the associated 2021 Star Ratings that are released prior to the annual coordinated election period for the 2021 contract year. 83 FR 16743 , Apr. 16, 2018