To amend title XIX of the Social Security Act to make permanent the State plan amendment option to provide medical assistance for certain individuals who are patients in certain institutions for mental diseases, and for other purposes.

This bill permanently allows state Medicaid programs to receive federal payment for substance-use disorder services that are provided at institutions for mental diseases (IMDs) for individuals aged 21 to 64. The bill also extends the maximum length of stay over a 12-month period from 30 days to 45 days. In addition, the bill provides statutory authority for a 2018 letter from the Centers for Medicare & Medicaid Services that provided for Medicaid demonstration programs for IMD mental health services for adults and children; the bill similarly increases the average length of stay under such programs to 45 days.