MT HB398

Health insurers must honor prior authorization certifications from a previous insurer for at least the first 3 months when a covered person changes health plans, provided services are covered under the new plan

Adverse determinations (coverage denials) must be made by a physician when the request comes from a physician, or by a health professional licensed in the same profession as the requesting provider; reviewers must have experience treating the relevant medical condition

Prior authorization validity periods increased from 3 months to 6 months for standard health care services, and set at 12 months for chronic conditions (defined as conditions lasting 1 year or more requiring ongoing medical attention)

Grievance reviews must be conducted by a physician with a nonrestricted license who specializes in the diagnosis and treatment of the condition being treated

Effective date: January 1, 2026