A Practice Note addressing requirements under the Mental Health Parity and Addiction Equity Act (MHPAEA) for group health plans and health insurers that provide both medical/surgical (M/S) benefits and either mental health or substance use disorder (MH/SUD) benefits. This resource, one of several companion resources on mental health parity, addresses MHPAEA's rules regarding nonquantitative treatment limitations (NQTLs) and related litigation.