How Medicare rehab coverage actually works

Three federal laws govern what Medicare must cover for substance use disorder. The Mental Health Parity and Addiction Equity Act (MHPAEA, 2008) requires coverage at parity with medical — same copay tier, same day limits, same prior-auth rules. The Affordable Care Act (2010) designates addiction treatment as an Essential Health Benefit, meaning marketplace plans must include it. 42 CFR Part 2 restricts how treatment records can be shared, even with insurers.

In practice, Medicare plans cover the ASAM continuum of care: medical detox (5–10 days, almost always pre-authorized for opioids, alcohol, or benzodiazepines), residential (30–90 days, requires documented medical necessity), PHP and IOP (partial day or 9–20 hrs/week), and standard outpatient counseling. MAT — buprenorphine, methadone, and naltrexone — is covered without prior authorization on most plans since it’s FDA-approved and outcome-proven.

In-network vs out-of-network

Medicare’s in-network treatment centers have pre-negotiated rates; your cost is typically a deductible + coinsurance (10–40% of the negotiated rate after deductible is met). Out-of-network coverage exists but you pay the difference between the facility’s billed rate and what Medicare allows — can be 2–3x in-network cost. Always verify before admission. Our facility directory lets you filter by Medicare specifically.

Pre-authorization and denials

Residential and inpatient treatment almost always require pre-authorization. Medicare may deny or limit coverage if they consider a lower level of care "medically appropriate." You have appeal rights under MHPAEA: insurers must use the same clinical-necessity standards for addiction as for medical conditions. If denied, escalate through the facility’s utilization review team — the vast majority of appeals succeed with proper clinical documentation. Call (833) 567-5838 for help navigating a denial.