Yes, inpatient rehab is covered by most health insurance plans in the United States. Federal law requires marketplace and employer-sponsored plans to include both substance use disorder treatment and rehabilitative services as essential health benefits. That said, the amount you’ll pay out of pocket, the length of stay your plan approves, and the hoops you’ll need to jump through vary significantly depending on whether you have private insurance, Medicare, Medicaid, or military coverage.
What Federal Law Requires
The Affordable Care Act lists ten categories of essential health benefits that non-grandfathered plans in the individual and small group markets must cover. Two of those categories directly apply here: “mental health and substance use disorder services including behavioral health treatment” and “rehabilitative and habilitative services and devices.” This means your plan cannot simply exclude inpatient rehab from coverage altogether.
On top of that, the Mental Health Parity and Addiction Equity Act requires insurers to treat mental health and substance use disorder benefits the same way they treat medical and surgical benefits. In practical terms, your insurer cannot charge you a higher copay for a rehab stay than it would for a comparable medical hospitalization. It also cannot impose stricter visit limits or require more burdensome prior authorization steps for addiction treatment than it does for other conditions. Under 2024 regulations, plans must actually collect data and document that their approval processes for behavioral health services are no more restrictive than those for physical health services.
Private Insurance: HMOs, PPOs, and Prior Authorization
If you have employer-sponsored or marketplace insurance, your plan type shapes how the approval process works. With an HMO, you typically need a referral from your primary care provider before entering inpatient rehab. With a PPO, referrals generally aren’t required, and you have more flexibility to choose a facility, though using an out-of-network center will cost significantly more.
Nearly all private plans require prior authorization for inpatient rehab. Your treatment provider usually handles this by submitting clinical documentation to the insurer before admission (or shortly after an emergency admission). The insurer then decides whether inpatient care is “medically necessary” for your situation, as opposed to a less intensive outpatient program. This is the step where denials most commonly happen, so it’s worth understanding how insurers make that call.
How Insurers Decide Your Level of Care
Most insurance companies use the ASAM Criteria, developed by the American Society of Addiction Medicine, to determine whether you qualify for inpatient versus outpatient treatment. It’s the most widely used standard for placement decisions in addiction care. A clinician evaluates you across several dimensions: the severity of your withdrawal risk, your medical conditions, your emotional and behavioral stability, your readiness for treatment, your risk of relapse, and your living environment. Dimensions one through five drive the level-of-care recommendation.
If your assessment shows you need 24-hour medical supervision, structured programming, or removal from an unsafe living situation, you’re more likely to be approved for inpatient care. If an insurer determines that outpatient treatment could address your needs, they may deny coverage for a residential stay. This doesn’t mean you can’t appeal. Denials based on medical necessity are among the most common reasons people file insurance appeals, and parity law gives you strong grounds if the insurer is applying stricter standards than it would for a comparable medical condition.
How Long Insurance Typically Covers
Private insurers rarely approve an open-ended inpatient stay upfront. The standard approach is to authorize an initial period, then require re-authorization at regular intervals, often every 30 days or sooner. At each review, your treatment team submits updated clinical information showing you still meet the criteria for inpatient care. If the insurer determines you’ve stabilized enough to step down to a less intensive level, coverage for the inpatient stay ends.
This means a 28- or 30-day program might be fully covered, but a 60- or 90-day stay will require your treatment team to justify continued inpatient care at each checkpoint. Some people find their coverage shifts to outpatient or intensive outpatient programs partway through, which can feel abrupt but reflects how the re-authorization process works in practice.
Medicare Coverage and Costs
Medicare Part A covers inpatient rehabilitation when a doctor certifies that you need intensive rehabilitation, ongoing medical supervision, and coordinated care from multiple providers. The cost-sharing structure is straightforward but has real dollar amounts worth knowing.
For 2026, you pay nothing for days 1 through 60 after meeting the Part A deductible of $1,736. From days 61 to 90, you pay $434 per day. Beyond 90 days, Medicare taps into your lifetime reserve days, which total 60 days across your entire lifetime. Each reserve day costs $868 in daily coinsurance. Once those reserve days are used up, you pay the full cost yourself. If you have a Medicare Supplement (Medigap) plan, it may cover some or all of these coinsurance amounts.
Medicaid: The IMD Exclusion
Medicaid coverage for inpatient rehab is complicated by a longstanding rule called the IMD exclusion. Medicaid traditionally cannot pay for care provided in “Institutions for Mental Diseases,” which are residential facilities with more than 16 beds that primarily treat mental health or substance use disorders. This rule has historically blocked Medicaid beneficiaries from accessing many inpatient rehab programs.
Starting in 2015, the federal government began encouraging states to apply for waivers to bypass this exclusion. By the end of 2020, 28 states had received waivers allowing Medicaid to cover substance use disorder treatment in these facilities. Whether you can use Medicaid for inpatient rehab depends heavily on your state. Some states cover residential stays of up to 30 days under their waiver, while others have different terms. Your state Medicaid office or a treatment facility’s admissions team can tell you what’s available where you live.
TRICARE for Military Families
TRICARE covers inpatient substance use disorder treatment for active-duty service members, retirees, and their families when the care is medically necessary. Both emergency and non-emergency inpatient services are covered, though special rules and limits apply. As with private insurance, prior authorization is typically required, and the treatment must meet medical necessity standards.
Reducing Your Out-of-Pocket Costs
Even with insurance, inpatient rehab can involve meaningful out-of-pocket expenses: your deductible, coinsurance or copays, and potentially charges from out-of-network providers. A few things can help keep costs down.
- Choose an in-network facility. Out-of-network stays can cost two to three times more in coinsurance, and some plans won’t cover them at all under an HMO structure.
- Verify benefits before admission. Call the number on the back of your insurance card and ask specifically about inpatient behavioral health or substance use disorder benefits. Get the deductible amount, coinsurance percentage, any day limits, and prior authorization requirements in writing.
- Ask the facility for help. Most rehab centers have admissions coordinators who verify insurance benefits and handle prior authorization as part of the intake process. They do this daily and know how to navigate the system.
- Appeal denials. If your insurer denies coverage, you have the right to an internal appeal and, if that fails, an external review by an independent third party. Parity law violations are a common and often successful basis for appeals.
Many facilities also offer sliding-scale fees or payment plans for the portion insurance doesn’t cover. Some states fund scholarship programs or grants for residents who need treatment but can’t afford their share of the cost. These options are worth asking about during the admissions process.