What do you do when a mental health claim is denied?

Is it a rejection or a denial? They recover differently.

A rejection never entered the payer’s adjudication system — it failed a front-end edit at the clearinghouse or the payer’s intake, so you correct the defect and resubmit. A denial was adjudicated and refused payment, so it needs an appeal, not a resubmission. Resubmitting a true denial as though it were a rejection produces the same outcome a second time and spends days you may not have.

Medicare draws the line explicitly, and its wording is the clearest statement of the mechanic we have found. A claim with missing, incomplete, or invalid required information is “returned as unprocessable,” and the Medicare Claims Processing Manual, Chapter 1 instructs contractors that they “shall not deny claims and afford appeal rights for incomplete or invalid information” (§80.3.2). A returned claim comes back with no appeal rights. There is nothing to appeal; there is something to fix.

That has a consequence for the filing clock that catches practices out. Chapter 24 of the same manual states it plainly: “‘Rejected’ or ‘returned’ transactions are not classified as ‘received’ by Medicare” (§60.1). A claim you believe you submitted six weeks ago was, as far as the payer is concerned, never submitted at all — and it has been aging toward its deadline the whole time. Commercial payers are not bound by the Medicare manual, but they operate the same front-end/adjudication split, so the same failure mode applies. This is why acknowledgment and rejection reports have to be read on the day they arrive rather than at month end, and it is the mechanical reason a claim ends up past its timely filing deadline without anyone deciding to let it.

For claims that were adjudicated, the reason lives in the remittance. The adjustment codes on the 835 are Claim Adjustment Reason Codes maintained by X12, which exist to say why a claim or service line “was paid differently than it was billed,” usually paired with a remark code carrying the detail. Reading them is the difference between knowing a claim denied and knowing whether it denied for something you can prove with a document or something you have to argue.

Why do outpatient mental health claims get denied?

The causes that repeat in an outpatient practice are procedural rather than clinical — but be careful how far you push that, because the best public data says the largest single category is one the insurers did not explain.

The most usable public breakdown is KFF’s analysis of 2024 HealthCare.gov data. Insurers of qualified health plans sold on HealthCare.gov denied 19% of in-network claims, with individual insurers ranging from 3% to 36%. Of those in-network denials, the reason insurers reported most often was “Other” at 36%, followed by administrative reasons at 25%, an excluded service at 13%, lack of prior authorization or referral at 9%, and medical necessity at only 5%. Those are shares of the denial reasons insurers tallied rather than of denied claims; KFF notes a claim may be denied for more than one reason and each is counted separately.

Three labels belong on that, and they matter more than the numbers. First, scope: these are HealthCare.gov marketplace plans, including state-based Marketplaces that run on the federal platform. They exclude state Marketplaces on their own systems and they exclude every group plan — which is where most of a commercial payer mix actually sits. Second, KFF’s 19% is a final-adjudication figure: “Claims that were initially denied, then subsequently resubmitted and paid, are not included as denied claims in the denial rate.” Third, there is no behavioral health denial rate in this data. Medical-necessity denials are reported separately for behavioral health and other services, but KFF publishes only the combined 5%, and insurers do not yet report whether denied claims overall were behavioral health — that begins with the plan-year 2027 certification process. Anyone quoting you a mental-health denial rate from this dataset is quoting something that is not in it — which is the same conclusion our guide to denial and A/R benchmarks reaches the long way round.

What we can describe without a statistic is the shape of the denials an outpatient mental health practice actually sees, because the causes repeat: eligibility that changed between the intake check and the session; a behavioral health carve-out routing the claim to a separate administrator with its own payer ID and filing rules, so a claim sent to the medical plan is answered by neither; authorized units exhausted partway through a course of treatment; telehealth billed with a place-of-service code or modifier combination the plan does not accept; a time-based psychotherapy code whose note does not document the time; and the rendering provider not enrolled with that specific payer or plan on that date. None of those is a clinical disagreement. All of them are knowable before the claim goes out, which is the subject of the companion piece on preventing denials rather than appealing them.

Who actually files the appeal — the practice or the patient?

Under the federal rules the appeal right belongs to the patient, and a practice normally exercises it as the patient’s authorized representative. This is the part most billing write-ups skip, and it is the part that gets an otherwise good appeal returned unread.

The federal external-review regulation at 45 CFR 147.136 defines the term directly: “Claimant means an individual who makes a claim under this section. For purposes of this section, references to claimant include a claimant’s authorized representative” (a)(2)(iii). The underlying claims-procedure rule at 29 CFR 2560.503-1 requires that a plan’s procedures “do not preclude an authorized representative of a claimant from acting on behalf of such claimant in pursuing a benefit claim or appeal” — and then adds the sentence that does the real work: “Nevertheless, a plan may establish reasonable procedures for determining whether an individual has been authorized to act on behalf of a claimant” (b)(4). The one place the regulation lets a clinician act without that paperwork is a claim involving urgent care, which a routine outpatient therapy claim is not.

In practice this means two tracks exist and they are not interchangeable. A practice can pursue the member appeal as the patient’s representative, which requires the plan’s designation form on file and reaches the federal timelines and external review below. Or it can use the payer’s own provider dispute or reconsideration process, which exists under the participation contract rather than the federal rules, and whose deadlines and levels are set by that contract and the provider manual. The second is usually faster for administrative denials and is what most billing work runs on. The first is what you need when the answer turns on whether the care was covered. Choosing the wrong one wastes a window; confirming which one a given payer expects, per plan, is an unglamorous but real part of the job.

How long do you have, and what happens at each step?

For an employer plan governed by ERISA, the federal floor is 180 days to appeal and, after that, four months to ask for an independent external review. Non-grandfathered commercial coverage outside ERISA reaches the same floor by a different route. The specific numbers are worth holding because they are the ones payers hold you to.

29 CFR 2560.503-1 requires plan procedures to “provide claimants at least 180 days following receipt of a notification of an adverse benefit determination within which to appeal” (h)(3)(i). That regulation is ERISA, so it reaches employer plans; coverage outside ERISA gets there another way, with 45 CFR 147.136 (b)(2)(i) applying the same requirements to group health insurance issuers and (b)(3) doing so for individual-market issuers. Grandfathered plans sit outside 147.136’s internal-appeal requirements, but an ERISA employer plan is subject to 2560.503-1 either way. A billed session is a post-service claim, so the plan then has 60 days to decide where it offers one level of appeal, or 30 days per level where it offers two (i)(2)(iii)(A). Those post-service figures are not the ones usually quoted online — the pre-service deadlines sit beside them in the regulation and are shorter — so check which row you are reading.

When internal appeals are exhausted, 45 CFR 147.136 gives the claimant four months from the notice to request an external review by an independent review organization, which must issue its decision within 45 days; an expedited review runs in “no event more than 72 hours.” If the IRO reverses, the plan “immediately must provide coverage or payment.” And there is a provision worth knowing about badly-run internal appeals: where a plan “fails to strictly adhere” to the internal process requirements, “the claimant is deemed to have exhausted” it and may go straight to external review — subject to a de minimis exception the regulation carves out in the same paragraph.

External review is also the least-used step by a wide margin. KFF counted at least 5,881 external appeals filed by HealthCare.gov enrollees in 2024, “or 4% of all upheld internal appeals” — both figures counting only insurers that reported at least ten external appeals, with values under ten suppressed. That is a count of what marketplace consumers did, not what practices or billers do — KFF publishes nothing about provider-initiated appeals — so read it as evidence that the step is rarely reached, not as a benchmark for your own appeal volume.

And if the payer is Medicare?

Medicare runs its own five-level process with its own clocks, published by CMS. It is slower than a commercial appeal and the later levels have a dollar floor, which decides for you how far a single therapy claim is worth taking.

From the CMS fee-for-service appeals flowchart, with the amounts shown on it for calendar year 2026: you have 120 days from the initial determination to request a redetermination by the Medicare Administrative Contractor, which has 60 days to answer. Then 180 days to request reconsideration by a Qualified Independent Contractor, also 60 days. Then 60 days to request a hearing before an Administrative Law Judge at the Office of Medicare Hearings and Appeals, which requires an amount in controversy of at least $200 and has a 90-day standard. Then 60 days to the Medicare Appeals Council (90 days), and 60 days to federal district court, where the amount in controversy must be at least $1,960. Both dollar thresholds are re-indexed every year, so confirm the current figures rather than carrying these forward.

One Medicare denial is outside all of that. A denial for late filing is not an initial determination and so, per CMS’s own manual, is not subject to appeal at all — we cover what that leaves you in the guide to timely filing denials. It is the clearest case on this page of a claim that is simply gone, and knowing which of yours are gone is worth more than another round of appeals on claims that are.

Which denied claims should you work first?

Sort by remaining window and by what the claim turns on. Age and dollar value are the two instincts, and both are wrong on their own: the oldest claim is often the one with no window left, and the largest is often the one that turns on a judgement the payer has already made twice.

The useful split is between denials you can win with a document and denials you have to argue. Eligibility, coordination of benefits, a claim sent to the wrong administrator under a carve-out, an authorization that was on file but not on the claim — these turn on a fact, and a fact you can attach. Medical-necessity denials turn on whether the record you already have meets the criteria the plan applied, which means the appeal is written against that plan’s published policy and the documentation is either there or it is not. The first group is where a fixed amount of time recovers the most money. The second is where prevention pays, because nothing added after the session improves the note.

It is worth being honest about the size of this pile, because the numbers usually quoted for it do not survive being traced. The AHIMA Journal reports, as an industry average it is repeating rather than a figure it measured, that as many as 60 percent of returned claims are never resubmitted, and that rework “averages $25 per claim for practices and a whopping $181 per claim for hospitals.” Read those with their labels on. The 60% is a ceiling, not a rate, and it covers claims the source calls returned rather than every denial. The $25 is the practice figure; the $181 is the hospital figure, and treating the two as one range — as this page and six others on this site previously did — overstates what rework costs a practice by roughly seven times. And the chain matters: AHIMA is a 2022 article, and its own bibliography attributes the 60% to a 2019 trade piece, and the rework costs to that same 2019 piece together with a 2017 one whose own headline figure is $118 per claim. It is the best-attributed version of a number that has no study behind it. Neither figure is behavioral-health specific, and neither tells you what is in your aging report — for which the only honest answer is to triage the report itself.

We have deliberately not published a recovery rate — what share of worked denials eventually pay. No credible public figure exists for it in this specialty, the numbers in circulation are trade estimates repeated from one vendor page to the next, and a billing company quoting you one is marketing rather than measuring.

Does mental health parity (MHPAEA) help you win a denial?

Rarely on a single claim. Parity is an argument about the rules a plan applies to mental health and substance use benefits compared with medical and surgical ones — not about whether one patient’s record supports one code on one date.

Where it can bear is when a plan’s behavioral health process is visibly more restrictive than its medical one: prior-authorization requirements that apply to therapy and not to comparable medical care, tighter medical-necessity criteria, more frequent re-review. That is a pattern argument, and it is usually a conversation with the plan or a regulator rather than a line in a claim appeal. The individual appeal still gets built on the record and the plan’s own criteria first.

The state of the rules is also worth stating plainly, because it moved and much of what is written online has not kept up. On May 15, 2025 the Departments of Labor, Health and Human Services, and the Treasury announced that they “will not enforce the 2024 Final Rule or otherwise pursue enforcement actions, based on a failure to comply that occurs prior to a final decision in the litigation, plus an additional 18 months.” That relief “applies only with respect to those portions of the 2024 Final Rule that are new in relation to the 2013 final rule,” and the Departments note that “MHPAEA’s statutory obligations, as amended by the CAA, 2021, continue to have effect.” As of September 12, 2026 that statement has not been withdrawn and no replacement rule has been published; the Department of Labor issued Field Assistance Bulletin No. 2026-03 on September 8, 2026, setting out how it will enforce the statutory requirements, which does not change the pause on the 2024 rule. This area is moving, so check its current state before relying on it.

Key takeaways

• Identify what you are holding before you write anything. A rejected claim is corrected and resubmitted; a claim returned as unprocessable carries no appeal rights at all; only an adjudicated denial is appealable.
• A rejected claim was never “received” — the filing clock kept running while you assumed it was in process. Read acknowledgment and rejection reports daily, not monthly.
• The best public reason breakdown is marketplace-only and has no behavioral health line in it. Treat any mental-health denial rate you are quoted as unsourced until shown otherwise.
• The federal appeal right belongs to the patient. A practice acts as the authorized representative, and the plan may require proof of that — or you use the payer’s contractual provider dispute process instead. They are different tracks with different deadlines.
• Commercial floor: 180 days to appeal, a 60-day decision on a post-service claim, then four months to request external review and 45 days for the IRO to decide.
• Medicare runs five levels with its own clocks and a dollar floor at the hearing level and again in federal court — and a late-filing denial is not appealable at all.
• Work by remaining window and by whether the denial turns on a document or an argument. The document ones recover the most money per hour.
• Parity is an argument about a plan’s rules, not a lever on one claim, and the 2024 rule’s new provisions remain under a federal non-enforcement policy.