The Quality Payment Program (QPP) was established by the Medicare Access and CHIP Reauthorization Act of 2015 (MACRA). The QPP consolidates existing Medicare pay-for-performance programs – the Physician Quality Reporting System, the Physician Value-based Payment Modifier, and the Medicare Electronic Health Record Incentive Program for Eligible Professionals – into a unified, cohesive program. The Merit-based Incentive Payment System (MIPS) is one of the two tracks of the QPP program, and the regulatory framework for MIPS was originally provided by MACRA and the Centers for Medicare & Medicaid Services' calendar year (CY) 2017 QPP final rule. This brief discusses changes to the original MIPS regulatory framework brought about by the Bipartisan Budget Act of 2018 and the CY 2018 QPP final rule.