Health plans deny a lot of claims, and almost nobody pushes back. In KFF’s 2026 analysis of federal transparency data covering the 2024 plan year, insurers selling qualified health plans on HealthCare.gov denied 19% of in-network claims, with individual insurer rates ranging from 3% to 36%. Consumers appealed fewer than 1% of those denials.
That gap is the opportunity. Of the roughly 263,000 internal appeals marketplace enrollees did file in 2024, insurers upheld 66%, meaning about one in three appealed denials got reversed. Once a case escapes the insurer and reaches an independent reviewer, the odds improve again: the Pennsylvania Insurance Department reported in April 2026 that its state-run external review had overturned 655 of 1,353 eligible cases, about 48%, since the process launched in 2024.
The appeals machinery is built on hard federal deadlines, and most of them run in your favor. Here is the order of operations.
Grievance vs. Appeal: Which One Do You Need?
These are two different channels, and filing the wrong one burns your clock.
An appeal contests a coverage decision. The plan refused to authorize or pay for a service, or billed you for a claim you already submitted. Medicare’s plain-English version of the test is the easiest to remember: appeal when the issue is a plan’s refusal to cover a service, supply, or prescription.
A grievance (often just called a complaint) is about service or quality. Rude or useless customer service, no realistic access to a specialist, a pharmacy stuck in a loop, or the plan slow-walking your appeal. Grievances build a paper trail regulators can act on, and they sometimes shake a problem loose, but a grievance will not overturn a denial.
If you want the claim paid, file the appeal. Nothing stops you from filing both.
Step 1: Read the Denial Notice and Find the Reason
The document that starts the clock is the adverse benefit determination. It arrives as a denial letter, and the same information usually appears on your explanation of benefits. Federal rules require it to state, in language you can actually understand, the specific reason for the denial, the specific plan provision behind it, what additional information would fix the claim, how the plan’s review process works, and your right to bring a civil action under ERISA section 502(a).
Plans that are not grandfathered under the ACA must go further: the notice has to include the denial code and its meaning, and the plan must hand over the diagnosis and treatment codes on request.
Work out which bucket you are in, because everything downstream depends on it. In the 2024 marketplace data, the reasons broke down roughly like this:
- Administrative reasons, 25%. Duplicate claims, missing information, untimely filing, unapproved provider records. Many of these never need an appeal at all. The provider’s billing office corrects and resubmits.
- “Other,” 36%. Insurers do not have to specify further, which is exactly why Step 2 matters.
- Excluded service, 13%. Difficult to win unless the plan document does not actually exclude what you got.
- No prior authorization or referral, 9%. Read prior authorization and how long prior authorization takes before you argue this one.
- Not medically necessary, 5%. Small share of the total, but these are the denials the external review system was built for.
Separately, if the denial is about an out-of-network provider you did not choose, check the No Surprises Act and our guide to balance billing first. Some of those balances are not legally yours to pay.
Step 2: Demand the Claim File and the Criteria (It Is Free)
Most appeals fail because people argue against a reason code instead of against the actual rule the insurer applied. You are entitled to see that rule.
Under 29 CFR 2560.503-1(h)(2)(iii), a plan must provide, on request and free of charge, reasonable access to and copies of all documents, records, and other information relevant to your claim. Paragraph (g)(1)(v) adds that if an internal rule, guideline, protocol, or clinical criterion was used, the plan must give you that criterion free of charge on request, and if the denial was based on medical necessity or an experimental exclusion, it must give you the scientific or clinical explanation applied to your circumstances. You can also demand the identity of any medical expert whose advice the plan obtained.
Put all of it in one written request:
- The complete claim file, including claim forms, notes, and internal review records.
- The exact medical-necessity or clinical criteria applied (name the vendor set if the letter mentions one).
- The specific plan or policy language relied on, with the page from the Summary Plan Description or certificate of coverage.
- The credentials of the reviewer who made the decision and any expert consulted.
The plan cannot bill you for this. The claims rule treats a fee charged as a condition of filing or appealing a claim as an unreasonable barrier. If the denial involves a drug, pull the formulary and the plan’s exception process at the same time, because a formulary exception request is often faster than a full appeal.
Step 3: File the Internal Appeal Within 180 Days
For group health plans, the federal rule gives you at least 180 days after receiving the denial to appeal, and HealthCare.gov applies the same 180-day window to marketplace coverage. Some plans allow longer, so check your Summary Plan Description, but treat 180 days as the floor and file early.
Here is the whole timetable in one place, as of September 2026:
| Stage | Your deadline to act | Plan or reviewer’s deadline to decide |
|---|---|---|
| Initial urgent care claim | Not applicable | 72 hours |
| Initial pre-service claim (prior authorization) | Not applicable | 15 days |
| Initial post-service claim (care already received) | Not applicable | 30 days |
| Internal appeal, urgent care | File immediately, orally or in writing | 72 hours |
| Internal appeal, pre-service | 180 days from the denial notice | 30 days (15 days per level if the plan uses two levels) |
| Internal appeal, post-service | 180 days from the denial notice | 60 days (30 days per level if the plan uses two levels) |
| External review, standard | 4 months from the final denial | 45 days |
| External review, expedited | File immediately | 72 hours |
Two structural details worth knowing. A plan cannot force you through more than two internal appeal levels before you can sue, and a plan that uses two levels gets only half the time for each one. And the person deciding your appeal cannot be the person who denied the claim or that person’s subordinate. If a medical judgment is involved, the plan must consult a health care professional with appropriate training who was not involved in the original decision.
For the letter itself, including the required elements and two copy-paste templates, use our insurance appeal letter templates. Keep a dated copy of everything you send.
Step 4: Escalate to Independent External Review
If the internal appeal fails, an outside reviewer with no financial stake in your plan gets to decide. This is where consumers do best.
You have 4 months from the date you receive the final internal denial to file the written request. Standard external reviews must be decided no later than 45 days after the request is received. Expedited reviews, for situations where waiting would seriously jeopardize your life, health, or ability to regain maximum function, must be decided within 72 hours, and in urgent cases you can run the external review at the same time as the internal appeal instead of waiting.
The decision binds the plan. If the reviewer overturns the denial, the insurer has to cover the service.
Three practical points:
- Not every denial qualifies. External review generally covers denials involving medical judgment, experimental or investigational determinations, and rescissions of coverage. A flat contract exclusion often is not eligible.
- Which process applies depends on your state and plan. Many states run their own qualifying external review. Where a state’s process does not meet federal standards, the issuer must use either the HHS-administered federal process (run by MAXIMUS Federal Services, requests accepted by portal, mail, fax, or email at 1-888-866-6205) or contract with an accredited independent review organization. Your final denial notice must tell you which one you get.
- The cost is near zero. The HHS-administered process is free. A state process or an issuer-contracted review organization cannot charge more than $25.
Step 5: Complain to the Regulator That Actually Has Jurisdiction
Regulators do not overlap neatly, and complaining to the wrong one costs weeks.
- Fully insured coverage (bought on the marketplace, directly from an insurer, or through an employer that buys an insurance policy) is regulated by your state department of insurance. That office also runs or assigns external review in most states.
- Self-funded employer plans, where the employer pays claims itself and an insurer only administers them, are governed by ERISA and overseen by the Department of Labor’s Employee Benefits Security Administration. Benefits advisors take questions at 1-866-444-3272. State external review usually does not reach these plans, which is why Pennsylvania, for example, tells self-funded enrollees to check with their employer first. Ask HR one question: is our plan self-funded or fully insured?
- Marketplace coverage issues that are about eligibility, enrollment, or subsidies rather than a claim go to the Marketplace itself, through CMS.
- Medicare runs on an entirely separate five-level track with its own deadlines. See our Medicare appeal guide.
Also file a grievance with the plan if it blew a deadline. If a plan fails to follow the claims rules, you can generally proceed straight to external review or to court without finishing the internal process.
Step 6: Handle the Bill While the Appeal Runs
An appeal can take two months. The bill does not pause itself, so work both tracks.
Ask for the cash or self-pay price. Providers frequently have a self-pay rate that is far below the gross charge on the bill, and sometimes below what the insurer would have allowed. Ask this question exactly: “If I pay this myself today, what is your self-pay or prompt-pay price?” Ask in writing that any payment be applied without prejudice to your pending appeal, so paying does not read as accepting the charge.
Apply for charity care. Nonprofit hospitals must have a financial assistance policy, and the income thresholds are much higher than most people assume. Start with hospital charity care and the charity care checker.
Get an itemized bill and audit it. Coding errors are common enough that the audit sometimes ends the dispute before the appeal does.
Set up a zero-interest payment plan rather than a credit product, and never let a provider move you onto a medical credit card while an appeal is live. The negotiation script gives you the phone language, and how to negotiate medical bills covers the rest.
For denied prescriptions, stack a formulary exception request with manufacturer help through prescription assistance programs.
The Bottom Line
A denial is an opening position, not a verdict. You have at least 180 days to appeal internally, 4 months to reach an independent reviewer whose decision the plan must obey, and a legal right to see the exact criteria used against you at no cost. Roughly a third of internal appeals get reversed and close to half of eligible external reviews go the consumer’s way, yet fewer than 1% of denied claims are ever appealed. The main thing standing between most people and a reversed denial is a letter nobody sent.