The bill amends Chapter 27-38.2 of the General Laws, which pertains to insurance coverage for mental illness and substance use disorders. It introduces new definitions, such as "Generally accepted standards of mental health and substance use disorder care" and "Medically necessary treatment of a mental health or substance use disorder," and updates the definition of "Mental health and substance use disorders" to include diagnostic categories from the World Health Organization and the American Psychiatric Association. The bill removes previous language that defined these disorders solely based on certain manuals and excluded tobacco and caffeine. It also introduces "Utilization review" and includes provisions regarding financial requirements, group health plans, and treatment limitations. The bill requires coverage for medically necessary treatment of mental health and substance use disorders for policies issued after January 1, 2025, and prohibits insurers from rescinding treatment authorization or limiting benefits based on public entitlement programs.

Furthermore, the bill mandates that utilization reviews for mental health and substance use disorders must use the most recent criteria and guidelines developed by the relevant clinical specialty's nonprofit professional association. Insurers are prohibited from using more restrictive criteria and must authorize the appropriate level of care. The bill requires insurers to sponsor education programs, provide training materials, track criteria usage, conduct reliability testing, and achieve a minimum interrater reliability pass rate. Violations of these provisions may result in fines up to $5,000 or $10,000 for willful violations. The bill applies to all insurance contracts offered, issued, or renewed on or after January 1, 2025, and will take effect upon passage.