Insurance: health insurers; prior authorization requirements for mental health and substance use disorder; modify. Amends sec. 3425 of 1956 PA 218 (MCL 500.3425).

HB 4683 requires Michigan health insurers to cover medically necessary mental health and substance use disorder treatments (including inpatient, intermediate, and outpatient care) without restrictive prior authorization practices. It mandates that insurers use clinical review criteria aligned with generally accepted medical standards, rather than arbitrary rules, when evaluating these services. The bill also prohibits insurers from making mental health coverage terms less favorable than those for other medical treatments. This directly affects health insurers operating in Michigan and patients seeking mental health or substance use disorder care through their insurance plans.