CMS Issues Proposed Rule for 2021 Outpatient Prospective Payment System and Ambulatory Surgical Center Payment System On August 4, 2020, the Centers for Medicare & Medicaid Services (CMS) published the calendar year (CY) 2021 Hospital Outpatient Prospective Payment System (OPPS) and Ambulatory Surgical Center (ASC) Payment System Proposed Rule. Among notable changes, CMS proposes to...