CMS announced its annual proposed OPPS/ASC rule in July 2023 and published the rule in the Federal Register on July 31, 2023. In addition to updating hospital and ASC payment rates, enhancing the hospital price transparency rules, and updating quality reporting programs, the proposed rule implements provisions in section 4124 of The Consolidated Appropriations Act (CAA) of 2023 establishing intensive outpatient program (IOP) for mental health and substance use disorder treatment as a Medicare covered benefit. The proposed rule sets out the benefits, requirements, and payment rates for IOP services furnished by hospital outpatient departments, Community Mental Health Centers, Rural Health Clinics, and Federally Qualified Health Centers. The proposed rule also updates payment rates for Partial Hospitalization Programs and clarifies that PHPs may provide substance use disorder treatment in addition to mental health treatment.