Does Health Insurance Have to Cover Mental Health?

Your insurer denied your therapy sessions, flagged your psychiatric medication as requiring prior authorization, or told you that residential treatment for addiction isn't "medically necessary." Meanwhile, you know that if you needed surgery or a hospital stay for a physical condition, the process would look nothing like this. You're not wrong to sense a double standard — and federal law says that double standard is illegal. This article explains exactly what your insurer is required to cover under the Mental Health Parity and Addiction Equity Act, why mental health claims still get denied at disproportionate rates, and the specific steps you can take to fight back.

What Does Federal Law Actually Require Insurers to Cover?

Most private health insurance plans and employer-sponsored health plans are legally required to cover mental health and substance use disorder (SUD) treatment on the same terms as physical medical care. The law that requires this is the Mental Health Parity and Addiction Equity Act (MHPAEA), which has been in effect since 2008 and was significantly strengthened by updates in 2024. The Centers for Medicare & Medicaid Services (CMS) oversees enforcement for marketplace plans, while the Department of Labor (DOL) enforces the law for employer-sponsored plans.

"Parity" means equal standing. Under MHPAEA, your insurer cannot apply stricter rules to mental health or SUD benefits than it applies to comparable medical or surgical benefits. That equality has to hold across three dimensions:

• Financial requirements — copays, coinsurance, and deductibles for mental health care must be no higher than what the plan charges for medical care in the same coverage tier.
• Quantitative treatment limits (QTLs) — visit limits, day limits, and dollar caps on mental health benefits cannot be lower than the limits applied to medical benefits. For example, if your plan covers unlimited physical therapy visits per year, it cannot cap outpatient therapy at 30 sessions.
• Nonquantitative treatment limitations (NQTLs) — this is the category where most violations hide. NQTLs are any non-numerical restriction on care: prior authorization requirements, medical necessity criteria, step therapy protocols (requiring you to try cheaper treatments first), network composition standards, and reimbursement rates. If your plan requires prior authorization for inpatient psychiatric care but not for inpatient surgery, that is a parity violation.

MHPAEA applies to most employer-sponsored group health plans with more than 50 employees, individual and small group marketplace plans, Medicaid managed care plans, and CHIP. It does not apply to short-term health plans or most plans with fewer than 50 employees, though some states have their own parity laws that fill those gaps.

Why Are Mental Health Claims Denied More Often?

Despite the law, mental health and SUD claims are denied at roughly two to three times the rate of comparable medical claims. The gap isn't accidental. It is built into how insurers write their internal coverage criteria.

The most common mechanism is a restrictive definition of "medical necessity." Every insurer uses medical necessity criteria to decide whether a treatment is covered. For physical conditions, insurers typically follow established clinical guidelines — for example, guidelines published by medical specialty societies. For mental health conditions, many insurers have historically used internal criteria that are stricter than what clinical guidelines support.

In 2019, a landmark federal court ruling in Wit v. United Behavioral Health found that United Behavioral Health had developed internal guidelines that prioritized cost containment over accepted standards of care, effectively denying coverage to tens of thousands of members with mental health and SUD diagnoses. The case exposed a widespread industry practice: writing medical necessity criteria that look clinical but are designed to produce denials.

Common targets for restrictive criteria include:

• Intensive outpatient programs (IOPs) and partial hospitalization programs (PHPs) for addiction or eating disorders
• Residential treatment for substance use disorders
• Applied behavior analysis (ABA) therapy for autism spectrum disorder
• Long-term therapy for OCD, PTSD, or bipolar disorder
• Psychiatric medication management visits beyond a set number per year

If your claim falls into one of these categories, a denial based on "not medically necessary" deserves a close look. The criteria your insurer used to make that decision may not hold up under scrutiny — or under the law.

How to Identify a Parity Violation

The most powerful tool available to you is a right you may not know you have: you can demand that your insurer hand over its nonquantitative treatment limitation (NQTL) analysis. This is a document — or set of documents — that shows how the insurer applies its coverage criteria to mental health benefits compared to medical and surgical benefits. The 2024 MHPAEA final rule requires plans to conduct and document this comparative analysis and provide it to participants upon request.

Here is a concrete example of how an NQTL analysis can expose a violation:

Suppose your plan requires prior authorization for inpatient psychiatric hospitalization but covers inpatient medical hospitalization without prior authorization. You request the NQTL analysis. The document shows that the plan applies prior authorization to mental health inpatient care using a set of criteria not applied to any comparable medical inpatient benefit. That is a textbook parity violation — the process for getting inpatient mental health care approved is more burdensome than the process for equivalent medical care.

To request the analysis, write to your insurer's member services department and specifically ask for "the comparative analysis of nonquantitative treatment limitations for mental health and substance use disorder benefits as required under MHPAEA and 29 CFR 2590.712." Keep the request in writing, and note the date. Plans are required to respond within a reasonable timeframe. If they refuse or provide something incomplete, that refusal itself is reportable to the DOL or your state insurance commissioner.

You can also look for simpler red flags without requesting a formal analysis. Review your Summary of Benefits and Coverage (SBC) — the standardized document your plan is required to provide — and compare what it says about prior authorization, visit limits, and cost-sharing for mental health versus medical benefits. Inconsistencies there may indicate a parity problem. For more on how prior authorization works and how to challenge it, see our guide on what prior authorization is and how to fight denials.

How to Appeal a Mental Health Denial

A denial is not a final answer. Federal law gives you the right to appeal, and the process has two stages: internal appeal and external review.

Step 1: Request the denial documentation

When you receive a denial, ask your insurer in writing for the specific clinical criteria it used to make the decision. Under ERISA and ACA regulations, they are required to provide this. You are looking for the exact standard your claim was measured against — not a summary, but the actual criteria. Compare those criteria to the clinical guidelines your provider follows (your psychiatrist or therapist can help you identify the relevant standards).

Step 2: Get a letter of medical necessity from your provider

Ask your treating clinician to write a detailed letter of medical necessity. This letter should document your diagnosis, the specific treatment recommended, why that level of care is clinically appropriate based on recognized standards (such as ASAM criteria for addiction treatment or APA guidelines for psychiatric care), and what harm could result from a lower level of care or no treatment. Specificity matters — a generic letter is easy to dismiss; a letter tied to clinical guidelines is not.

Step 3: File an internal appeal

Submit your appeal in writing with the letter of medical necessity, the clinical guidelines your provider cited, and any documentation comparing the insurer's mental health criteria to how it handles comparable medical benefits. If your denial involves a parity issue, say so explicitly — state that you believe the denial violates MHPAEA and explain why. Plans must complete internal appeals within 30 days for non-urgent care. For a detailed walkthrough of the general appeals process, see our guide on how to appeal a denied insurance claim.

Step 4: Request external independent review

If your internal appeal fails, you have the right to external review by an independent organization with no financial relationship to your insurer. Under ACA rules, external reviewers must apply clinical standards, not just the insurer's internal criteria. For MHPAEA violations specifically, external reviewers can order the plan to cover the care. File for external review within the deadline stated in your denial letter — typically 60 days from the final internal appeal decision.

Step 5: File a regulatory complaint

You do not have to wait until the appeals process is exhausted to file a complaint. If you believe your plan has violated MHPAEA, report it to the DOL (for employer-sponsored plans) or your state insurance commissioner (for individual and marketplace plans). The DOL's Employee Benefits Security Administration (EBSA) investigates parity violations and has the authority to require plans to change their criteria and pay claims. Complaints can be filed at dol.gov/EBSA or by calling 1-866-444-3272.

What If You Can't Find an In-Network Provider?

A plan that offers mental health benefits on paper but has no in-network mental health providers available in your area may also be violating parity rules — inadequate network access is an NQTL. If you're being pushed out of network for psychiatric care because no in-network providers are available, that situation has its own set of rights and remedies. Our guide on what to do when doctors won't accept your insurance covers the steps for requesting an in-network exception and using network adequacy rules to your advantage.

What to Do Right Now

If your mental health or SUD claim has been denied, start here:

1. Request your denial in writing with the specific clinical criteria used — not a summary.
2. Ask your treating provider for a detailed letter of medical necessity tied to clinical guidelines.
3. Write to your insurer requesting the NQTL comparative analysis for mental health benefits.
4. Compare what you receive to how the plan handles comparable medical benefits.
5. File an internal appeal within the deadline in your denial letter.
6. If the internal appeal fails, request external independent review immediately.
7. File a complaint with the DOL or your state insurance commissioner — you can do this in parallel with your appeal.

The law is on your side. Parity violations are common, they are documented, and regulators are actively enforcing against them. A denial is worth challenging, particularly when the care involves a serious diagnosis and significant ongoing costs. The process takes effort, but the legal framework exists precisely because insurers have demonstrated they will not apply equal standards without pressure to do so.

Sources: CMS Mental Health Parity Overview, DOL MHPAEA Enforcement — Employee Benefits Security Administration