Most health insurance plans in the United States are required by federal law to cover rehabilitation for substance use disorders. The Affordable Care Act classifies “mental health and substance use disorder services including behavioral health treatment” as one of ten essential health benefit categories that individual and small group market plans must include. That said, what “covered” looks like in practice varies widely depending on your plan type, your provider network, and the level of care you need.
What Federal Law Requires
Two major federal laws shape how insurers handle rehab coverage. The Affordable Care Act (ACA) requires non-grandfathered plans in the individual and small group markets to cover substance use disorder treatment as an essential health benefit. This applies to plans purchased through the Health Insurance Marketplace and most employer-sponsored plans.
The second law, the Mental Health Parity and Addiction Equity Act, prohibits insurers from placing stricter limits on addiction treatment than they do on medical or surgical care. If your plan covers 30 days of inpatient care for a physical condition, it cannot cap inpatient rehab at 14 days. Updated federal rules that took effect in November 2024 strengthened these protections significantly. Insurers are now required to collect data on how their policies affect access to mental health and substance use services compared to medical services, and they must take action to fix any meaningful gaps. Plans can no longer use hidden administrative barriers, like tougher pre-approval requirements or narrower provider networks, to make addiction treatment harder to access than comparable medical care.
How Medicare Covers Rehab
Medicare covers substance use disorder treatment under both Part A and Part B, though each covers different settings. Part A covers inpatient stays at a hospital or psychiatric facility when your doctor certifies you need intensive rehabilitation and continued medical supervision. Part B covers outpatient services like doctor visits, intensive outpatient programs, and partial hospitalization at hospitals, community mental health centers, and opioid treatment programs.
The cost structure for inpatient care under Medicare Part A works in benefit periods. In 2026, you pay a $1,736 deductible, then nothing for days 1 through 60. Days 61 through 90 cost $434 per day. Beyond that, you can draw on up to 60 lifetime reserve days at $868 per day. Once those reserve days are used up, you pay the full cost. Part B services follow a different structure, typically requiring you to pay 20% of the Medicare-approved amount after meeting your annual deductible.
Medicaid Coverage and Its Limits
Medicaid covers substance use treatment, but a rule known as the IMD exclusion creates a significant gap. The federal government will not reimburse states for care provided to adults aged 21 through 64 who are patients at residential facilities with more than 16 beds that primarily treat mental health or substance use conditions. This means if you’re on Medicaid and need residential rehab, your options may be limited to smaller facilities or outpatient programs, depending on your state. Some states have obtained federal waivers to work around this restriction, but coverage varies considerably by location.
Children under 21 and adults 65 and older are exempt from the IMD exclusion and can receive inpatient psychiatric and substance use treatment through Medicaid when it’s deemed medically necessary.
Private Insurance: HMO vs. PPO Differences
If you have employer-sponsored or marketplace insurance, your plan type determines both where you can go and what you’ll pay. HMO plans generally require you to use in-network providers and get referrals from your primary care doctor. If the rehab facility you want isn’t in your insurer’s network, an HMO typically won’t cover it at all.
PPO and POS plans offer more flexibility. You can go to out-of-network providers, but your costs will be higher. With out-of-network care, you’ll usually face a larger deductible, higher coinsurance, and you may also be responsible for the difference between what your insurer considers a reasonable charge and what the facility actually bills. In some cases, you can request that your insurer approve an out-of-network facility at in-network rates, particularly if no comparable in-network option is available.
What You’ll Pay Out of Pocket
Even with insurance, rehab involves cost-sharing. The three main components are your deductible (the amount you pay before insurance kicks in), your copay (a flat fee per visit, often around $30), and your coinsurance (a percentage of the cost, commonly 20%). These costs add up, especially for residential treatment that can last 30 to 90 days.
The good news is that all Marketplace plans have an out-of-pocket maximum. For 2026, that cap is $10,600 for an individual and $21,200 for a family. Once you hit that limit, your plan covers 100% of covered services for the rest of the year. If you’re facing an extended residential stay, you may reach your out-of-pocket maximum relatively quickly, which means the later portion of treatment costs you nothing.
Prior Authorization and Medical Necessity
Most insurers require prior authorization before they’ll approve coverage for rehab, especially for residential or inpatient treatment. This means your healthcare provider submits paperwork justifying why you need the specific level of care being requested. The insurer then reviews the request and decides whether to approve it based on their medical necessity criteria. This process can take several days, and denials are common for higher levels of care when the insurer believes a less intensive option would be appropriate.
One important exception: emergency services, including emergency detox, do not require prior authorization under the ACA. If you go to an emergency room for withdrawal symptoms or an overdose, your plan must cover it regardless of whether anyone called the insurer first. Coverage after that initial emergency stabilization, such as transitioning into a residential program, will typically require authorization.
If your insurer denies coverage, you have the right to appeal. Internal appeals go back to the insurer for a second review, and if that fails, you can request an independent external review. Denials based on medical necessity are frequently overturned on appeal, so it’s worth pursuing if you believe the recommended level of care is appropriate.
How to Verify Your Coverage
Before choosing a rehab program, call the member services number on the back of your insurance card and ask specific questions. Find out whether substance use treatment requires prior authorization, what levels of care are covered (detox, residential, partial hospitalization, intensive outpatient, outpatient), whether the facility you’re considering is in-network, and what your deductible and coinsurance will be. Many rehab facilities also have admissions staff who will verify your insurance benefits for you as part of the intake process.
If you’re uninsured, state-funded treatment programs exist in every state, and federally qualified health centers offer sliding-scale fees based on income. SAMHSA’s national helpline (1-800-662-4357) provides free referrals 24 hours a day.