If you get health coverage through a private employer, your denial is governed by a federal statute most people have never heard of — and that statute hands you two things insurers would rather you not use. You get at least 180 days to appeal. And you can demand every document, record, and internal guideline the plan relied on, free of charge.
That second right is the one that wins appeals. You are entitled to see the reasoning before you rebut it. This guide covers how ERISA appeals actually work, the deadlines on both sides, and how to write the letter — or you can have our insurance appeal tool draft it from your denial notice.
What you’re actually facing
ERISA — the Employee Retirement Income Security Act — governs employee benefit plans offered by private employers. If your health insurance comes through a private-sector job, your claim almost certainly falls under it.
It does not cover: plans for government employees, church plans, individual policies you bought yourself, or Marketplace coverage. Those run on state insurance law or ACA rules instead. Much of the strategy below still applies, but the specific citations do not, so check which regime you are in before you write.
An ERISA appeal is not a customer-service escalation. It is a formal administrative process with defined steps, and it has a consequence people rarely appreciate: the record you build during the appeal is generally the record a court would later review. If you eventually sue under ERISA § 502(a), a judge will typically be looking at the file that existed when the plan made its final decision — not new evidence you produce later.
That single fact should change how you approach this. You are not writing a complaint letter. You are building the evidentiary record while the window to build it is still open.
The law on your side
29 U.S.C. § 1133 — ERISA § 503, the claims-procedure requirement. Every employee benefit plan must “provide adequate notice in writing to any participant or beneficiary whose claim for benefits under the plan has been denied, setting forth the specific reasons for such denial, written in a manner calculated to be understood by the participant,” and must afford “a reasonable opportunity … for a full and fair review.”
Two words there are load-bearing. Specific — a denial that says “not medically necessary” without explaining what criteria were applied and how your case failed them is arguably not specific reasons. And full and fair — which the implementing regulation fleshes out considerably.
Your deadline: at least 180 days. The Department of Labor states plainly that you have at least 180 days to file an appeal, and directs you to check your Summary Plan Description in case your plan allows longer. Count from the date of the denial notice.
The plan’s deadlines to decide your appeal, per DOL guidance on the claims regulation:
| Claim type | Plan must decide the appeal within |
|---|---|
| Urgent care | 72 hours |
| Pre-service | 30 days |
| Post-service | 60 days |
A plan may extend these only with your consent. It cannot unilaterally take longer.
Your right to the file. DOL again, unambiguously: “The plan must provide you copies of documents, records, and other information relevant to your claim for free if you request them. You can also request the identity of any medical or vocational expert whose advice was obtained by the plan.”
Who reviews the appeal. On appeal your claim “must be reviewed by someone new who looks at all of the information submitted and consults with qualified medical professionals if a medical judgment is involved.” That reviewer “cannot be the same person who made the initial decision or that person’s subordinate, and the reviewer must give no consideration to the initial decision.”
Read that last clause again. The appeal is meant to be a fresh look, not a rubber stamp of the first one.
Step 1: Identify your plan type and your deadline
Before anything else, answer two questions.
Is this an ERISA plan? Private employer coverage: almost certainly yes. Government or church employer, individual policy, Marketplace plan: no. If you are unsure, your Summary Plan Description will usually say, and a plan that is subject to ERISA is required to give you an SPD on request.
Is this a pre-service or post-service claim? Pre-service means you have not received the care yet — a denied prior authorization. Post-service means the care happened and payment was refused. The distinction sets the plan’s decision deadline, and it changes urgency: a pre-service denial for treatment you still need may qualify for the urgent-care track and its 72-hour clock.
Then find your own deadline. Look at the denial notice — it must tell you how to appeal. Count 180 days from the notice date and write that date down. Check the SPD in case your plan grants more.
Do not use the full 180 days. Start now. You will need time to get records from the plan and a letter from your doctor, and neither moves quickly.
Step 2: Demand the claim file — before you write the appeal
This is the step that separates appeals that work from appeals that do not, and it is the one almost everyone skips.
Send a short written request, immediately and separately from your appeal, asking for everything relevant to your claim. Specifically:
- The complete claim file for this claim.
- The specific plan provisions relied on in denying it.
- Any internal rule, guideline, protocol, or clinical criterion applied — including the vendor criteria sets many plans license rather than write themselves.
- The identity and credentials of the medical professional who reviewed the claim, and any report they produced.
- Any medical or vocational expert whose advice the plan obtained.
The plan must provide these free. Say in the request that you are asking under ERISA § 503 and the claims-procedure regulation, and that you are requesting them in connection with your appeal.
Why this matters so much: a denial letter tells you the conclusion. The claim file tells you the reasoning — which criteria were applied, what the reviewer actually read, whether the reviewer was a specialist in the relevant field or a generalist working from a checklist. You cannot rebut criteria you have never seen. Insurers know this, which is why the default denial letter is vague.
If the plan does not produce the file, document that. A refusal to provide relevant documents is itself a departure from the full-and-fair-review requirement.
Step 3: Get a letter of medical necessity from your treating physician
The single strongest attachment an appeal can carry is a letter from the doctor who actually examined you.
It should be specific rather than general. Ask your physician to state their credentials and treating relationship; describe your diagnosis and clinical history; explain why this specific treatment is medically necessary for you; address the plan’s stated denial reason directly; cite clinical guidelines or literature where relevant; and describe what happens if the treatment is denied or delayed.
Give your doctor a copy of the denial letter and the criteria from the claim file. A letter that says “the patient needs this” is worth far less than one that says “the plan’s criteria require documented failure of conservative therapy; the patient completed twelve weeks of physical therapy from January to March 2026 with no improvement, as documented in the attached records.”
Doctors’ offices are busy and these requests are common. Ask early, be specific about what you need, and offer to draft a starting point they can edit and sign.
Step 4: Write the appeal letter
Structure it so a reviewer who reads only the first page still knows what you want.
- Identify the claim in the opening lines — member ID, claim number, dates of service, provider.
- State that this is a formal appeal under ERISA § 503 and the plan’s claims procedure, and that you are requesting a full and fair review.
- Quote the denial reason verbatim, then rebut that specific reason. Not denials in general — the exact stated basis.
- Apply the plan’s own criteria to your facts, using the guidelines you obtained from the claim file.
- Reference your attachments — the physician letter, medical records, relevant literature.
- Note any procedural failures, such as documents you requested and did not receive, or a reviewer without relevant specialty credentials.
- State the remedy and the deadline — the claim you want paid, and the date by which the plan must decide.
Attach everything you want considered. Because the administrative record generally becomes the record on review, evidence you leave out now may be evidence you cannot introduce later.
Send it certified mail, return receipt requested, to the exact address in the denial notice, and keep a complete copy of everything you sent.
Getting the statutory framing and the criteria-to-facts argument right is most of the work. Our appeal letter generator builds that structure from your denial letter and records, and you can preview it before paying.
Sample appeal letter excerpt
Re: Appeal of Claim No. 2026-4471-XX — Member ID 88-XXXXXXX Date of Service: January 22, 2026 · Provider: Yuma Regional Orthopedics
I am filing a formal appeal of the above claim under ERISA § 503 (29 U.S.C. § 1133) and the plan’s claims procedure, and I request a full and fair review by a reviewer with appropriate clinical expertise.
Your notice dated February 4, 2026 states the claim was denied because the service was “not medically necessary under plan criteria.” The clinical criteria you provided in response to my document request require documented failure of conservative therapy prior to authorization.
That criterion is satisfied. As documented in the attached records, I completed twelve weeks of physical therapy between October 2025 and January 2026 with no measurable improvement in range of motion. The attached letter from Dr. A. Reyes, my treating orthopedic surgeon, states that continued conservative management is not clinically appropriate.
I further note that the reviewing clinician identified in the claim file is credentialed in family medicine. I request that this appeal be reviewed by a board-certified orthopedic specialist.
I request that the denial be reversed and the claim paid in full.
FightThis drafts the full version from your documents — preview free.
If it doesn’t work
A second denial is not the end of the process. Be clear-eyed, though: across the individual market, KFF’s analysis of federal transparency data found insurers upheld 66% of internal appeals in 2024. Roughly one in three got a different answer — meaningfully better than zero, and worse than most people assume.
External review. If your plan is subject to the ACA’s review requirements, you may be entitled to an independent external review by a reviewer who does not work for your insurer, and that decision binds the insurer. External review is used far less than it could be — KFF found Marketplace enrollees filed at least 5,881 external appeals in 2024, about 4% of upheld internal appeals. Independent research suggests the odds there are real: a 2025 Health Affairs study of external review decisions in four states found almost half overturned the initial denial.
Department of Labor. ERISA plans are enforced by DOL’s Employee Benefits Security Administration, and its benefits advisors will talk to participants directly about claims problems.
State insurance commissioner. Useful for non-ERISA and fully insured plans; less so for self-funded ERISA plans, which states generally cannot regulate.
ERISA § 502(a) lawsuit. You generally must exhaust the plan’s internal appeals first — which is another reason to do the appeal properly rather than quickly. Your appeal letter and the documents you attached become the core of what a court reviews.
If the denial involves an out-of-network provider at an in-network facility, or emergency care, check whether the No Surprises Act protections apply — that may remove the balance entirely rather than requiring an appeal. And if what you are facing is a bill rather than a coverage denial, our guide to fighting medical bills covers that separately.
The bottom line
ERISA gives you a long deadline, a right to the insurer’s own reasoning, and a requirement that a different person with relevant expertise looks at your file. Those are real procedural advantages, and they are largely unused: KFF found consumers appeal fewer than 1% of denied claims.
The insurer’s arithmetic depends on that. A denial costs them nothing if nobody answers it.
This article is general information, not legal advice. ERISA deadlines are strict and exhausting the internal appeal process affects your later options — for large claims or complex situations, consult an attorney who handles ERISA benefits cases.