My Insurance Denied My Claim: The 6-Step Playbook
Fewer than 1% of denied marketplace claims are appealed. Insurers overturned 44% of the ones that were (KFF, 2023 data). The 6-step playbook, the 180-day clock, and the federal rule behind your right to appeal.
Your insurer is required by federal law (45 CFR §147.136 and 29 CFR §2560.503-1) to give you at least 180 days to file an internal appeal. In HealthCare.gov plans, insurers upheld 56% of appealed denials in 2023 and overturned the other 44% (KFF). In Medicare Advantage, 80.7% of appealed prior-authorization denials were overturned in 2024 (KFF). The single most important thing today is read the denial letter, identify the reason code, and start the appeal clock, most denials become permanent because nobody filed, not because the denial was correct.
KFF's analysis of HealthCare.gov plans found that insurers denied 20% of in-network claims in 2023, roughly one in five. Of the 86 million denied claims, consumers appealed fewer than 1%. Insurers then overturned 44% of the appeals they received. External review is a separate lane after that: CMS suppresses the small numbers in the marketplace file, so no national reversal rate can be calculated, but the states that publish their own figures range from 17% to 73%. The system is built on the assumption that you will not file.
At-a-glance: the 6 steps
- Read the denial letter slowly. Find the exact reason code and the appeal deadline.
- Request your full claim file in writing within 7 days. This is your federal right.
- Force disclosure of the clinical criteria the carrier used. They almost never include it; the law says they must give it when you ask.
- Get a Letter of Medical Necessity (LMN) from your treating doctor matching each criterion.
- File the internal appeal, by certified mail, fax confirmation, or the carrier's portal with a screenshot.
- If internal appeal fails, file external review (IRO). This is binding on the carrier and has higher reversal rates than internal review.
Step 1: Read the denial letter slowly
The denial letter (sometimes an Explanation of Benefits with a denial code, sometimes a separate Adverse Benefit Determination Notice) must include by law under 45 CFR §147.136(b)(2)(ii)(C): the specific reason for the denial, the plan provision the denial relies on, information about internal appeals and external review, and the contact for any consumer-assistance program in your state.
If your letter is missing any of these, that's itself an appealable procedural failure, and worth noting in your appeal.
Take a marker. Highlight the denial date (this starts the 180-day clock), the reason code or category, the dollar amount, the appeal address or portal URL, and the member-services phone number.
Step 2: Request your claim file in writing
Under 29 CFR §2560.503-1(h)(2)(iii) (ERISA) and 45 CFR §147.136(b)(2)(ii)(C) (ACA-governed plans), you have the right to your full claim file free of charge, including all claim notes, internal medical-review opinions, the specific clinical criteria applied, peer-review documents, and communications between carrier and provider.
Send a short written request to the appeals address. Email is fine if the carrier accepts it; certified mail is better. Include your member ID, claim number, and denial date. The carrier generally has 30 days to produce the file.
Step 3: Force disclosure of the clinical criteria
Carriers issue tens of thousands of 'not medically necessary' denials per day, and the initial letter almost never includes the specific clinical criteria used. Those criteria, often called Medical Coverage Policies, Clinical Policy Bulletins, or Medical Necessity Guidelines, are the document the carrier's reviewer consulted. When you obtain them, you have a checklist to rebut. Without them, your appeal is shouting into a void.
For most denials, the criteria are already published, they just weren't named in your letter. Cross-reference the procedure or diagnosis to the carrier's published policy and you'll often find the exact criteria they (should have) applied.
| Carrier | Criteria-document name |
|---|---|
| UnitedHealthcare | Medical Policies (uhcprovider.com) |
| Aetna | Clinical Policy Bulletins (CPBs) |
| Cigna | Coverage Policies |
| Anthem / Elevance | Clinical UM Guidelines |
| Humana | Medical Coverage Policies |
| Kaiser Permanente | Internal, request via member portal |
Step 4: Get a Letter of Medical Necessity (LMN)
A treating physician's letter of medical necessity is the single most important document in most appeals. The LMN does the work the patient cannot, it speaks the carrier's clinical language.
The LMN should contain: identifying info (patient, member ID, claim, codes), concise clinical history, the carrier's criteria addressed line by line, citations to professional guidelines, a clear signed statement of medical necessity, and the doctor's NPI and contact.
The most effective ask is to send the doctor a draft letter you've already structured, they edit, sign, return. Apellica drafts the LMN for the doctor's signature as part of the appeal-prep service.
Step 5: File the internal appeal
You generally have 180 days from the denial date to file an internal appeal under ACA-governed plans. Some Medicare Advantage plans give 60 days. Always check the letter.
The appeal package: cover letter referencing claim number and denial reason, the Letter of Medical Necessity, point-by-point criteria-match document, supporting clinical records, and citations to peer-reviewed evidence.
| Method | Pros | Cons |
|---|---|---|
| Carrier online portal | Date-stamped, fast | Verify upload received, screenshot |
| Certified mail with return receipt | Legally durable | 7-10 days slower |
| Fax with confirmation | Same-day, paper trail | Some carriers' fax queues unreliable |
Step 6: External review (IRO) if internal appeal fails
If your internal appeal is upheld, you can request external review by an Independent Review Organization (IRO). The IRO is a third-party panel of physicians; its decision is binding on the carrier.
External review covers denials based on medical necessity, experimental/investigational status, and rescissions. Federal external review under 45 CFR §147.136(d) applies to ERISA self-funded plans and states without qualifying programs. State external review covers fully-insured plans.
| Situation | IRO must decide within |
|---|---|
| Standard external review | 45 days (federal) / 30 days (most states) |
| Expedited urgent | 72 hours |
Frequently asked questions
How long do I have to appeal a denied insurance claim?
For most plans governed by the ACA, you have 180 days from the date on the denial notice to file an internal appeal. Self-funded ERISA plans also follow the 180-day floor under 29 CFR §2560.503-1. Some Medicare Advantage plans give 60 days. Check the denial letter, missing the deadline usually forfeits the right to appeal.
Do I need a lawyer to appeal an insurance denial?
No, most internal appeals don't require a lawyer. The federal regulations are designed for patients to navigate themselves. Lawyers become more useful at external review or moving toward litigation under ERISA. Apellica prepares the evidence-based appeal documents but is explicitly not a law firm.
What's the difference between internal appeal and external review?
Internal appeal is the carrier reviewing its own decision (usually by a different medical reviewer). External review is an independent third-party physician panel (the IRO) reviewing the case; its decision is binding on the carrier. You must usually complete internal appeal before requesting external review.
How much does it cost to appeal?
Internal appeals are free under federal law, the carrier cannot charge you. External review through state programs is usually free; some states (e.g., New York) charge a small fee waived for hardship. Federal external review is free. Hiring an attorney or service costs separately.
What happens if my appeal is denied again?
If your internal appeal is upheld, request external review (IRO). If the IRO upholds, your options narrow but aren't zero: civil action under ERISA (self-funded plans) or under state law (fully-insured plans). Consult an attorney at that point.
Can the insurance company retaliate if I appeal?
No. Under federal law and most state insurance codes, carriers cannot retaliate (e.g., cancel coverage, raise premiums) because you exercised your appeal rights. Document any retaliation and file a complaint with your state DOI.
What if my plan is a self-funded employer plan (ERISA)?
ERISA self-funded plans follow 29 CFR §2560.503-1. The 180-day appeal floor still applies. ERISA plans must offer federal external review under §147.136(d). Your plan's Summary Plan Description describes the exact procedure.
What's an 'adverse benefit determination'?
The legal term for a denial. Under 29 CFR §2560.503-1, it includes a denial, reduction, or termination of, or a failure to provide or make payment for, a benefit.
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