Michelle Alyssa Go Act This bill removes certain limitations relating to Medicaid coverage of services provided in institutions for mental diseases (IMDs). Current law generally prohibits federal payment under Medicaid for services provided in IMDs with more than 16 beds for individuals under the age of 65 (although states may receive payment through certain mechanisms, such as through a Medicaid demonstration waiver). The bill removes the age limitation and allows any institution to qualify as an IMD, regardless of the number of beds, if it primarily treats individuals with mental diseases and meets nationally recognized standards for mental health or substance use disorder programs, as approved by the Centers for Medicare & Medicaid Services.