The U.S. Departments of Health and Human Services (HHS), Labor, and Treasury (often referred to as the "Tri-Agencies") published a group of final rules on Sept. 9, 2024, to amend and add to existing regulations implementing the Mental Health Parity and Addiction Equity Act (MHPAEA). First signed into law in 2008, MHPAEA aims to prevent health insurance plans from treating mental health and substance use disorder (MH/SUD) benefits less favorably than medical/surgical benefits. It built on the foundation laid by the Mental Health Parity Act of 1996, which prohibited large group health plans from imposing more restrictive annual or lifetime dollar limits on mental health benefits as opposed to those levied against medical/surgical benefits.