Effective January 1, 2023, Illinois law will require health insurers to cover mental health services. In August, Governor J.B. Pritzker signed HB 2595, Public Act 102-0579, which will require health insurers to “cover medically necessary services and treatments for mental, emotional, nervous, or substance use disorders and conditions.” The new law will improve the transparency of coverage decisions by establishing clear “definitions and standards” for when treatment and services are medically necessary. Additionally, the law requires Medicaid MCOs and commercial insurers to utilize “publicly available guidelines published by nonprofit clinical societies” when determining medical necessity.