Research · 2024 data
The Denial & Appeal Landscape
What the public data says about how often U.S. health insurers deny claims, how rarely people fight back, and how often those who do, win.
Quick Answer
In 2024, HealthCare.gov marketplace insurers denied 19% of in-network claims (about 85 million claims), yet consumers appealed fewer than 1% of those denials. When people did appeal, insurers upheld 66% of internal appeals. The lesson in the data: denials are common and appeals are rare. Every figure on this page is cited to KFF/CMS public data.
The appeal gap
Three numbers tell the story of HealthCare.gov marketplace denials in 2024. Insurers denied 19% of in-network claims. Of those roughly 85 million denied claims, consumers appealed fewer than 1%. And of the internal appeals that were filed, insurers upheld 66% (KFF does not break down the remainder).
The gap between how often claims are denied and how often denials are challenged is enormous — and it matters, because a denial that is never challenged simply stands. A denial is the start of a negotiation, not the end of one.
Key figures (2024)
Every figure links to its public source. These figures come from KFF's analysis of the CMS Transparency in Coverage Public Use File for HealthCare.gov marketplace plans in 2024.
| Figure | What it measures | Source |
|---|---|---|
| 19% | Average in-network claim denial rate for HealthCare.gov marketplace insurers | KFF, 2024 |
| ~85 million | In-network claims denied by HealthCare.gov marketplace insurers | KFF, 2024 |
| <1% | Share of denied in-network claims that consumers appealed (at least 262,982 appeals) | KFF, 2024 |
| 66% | Share of appealed denials that insurers upheld on internal appeal (KFF does not break down the rest) | KFF, 2024 |
| 5,881 | External (independent) appeals filed by marketplace enrollees — the external overturn rate is suppressed in the public data | KFF, 2024 |
Why in-network claims were denied
Share of 2024 HealthCare.gov in-network denials by reported reason. Note that the single largest category is "other / not specified," a transparency gap KFF highlights. Source: KFF, 2024.
The under-used escape hatch: external review
When an internal appeal fails, federal law gives most plan members a second shot: an independent external review by a reviewer with no ties to the insurer, whose decision is binding on the plan (45 CFR 147.136; HealthCare.gov). Yet marketplace enrollees filed only 5,881 external appeals in 2024 — a rounding error against 85 million denials.
Federal rules generally give you up to four months after a final internal denial to request external review. It is one of the most powerful — and least used — consumer protections in American health insurance.
Methodology & honesty note
- All figures are KFF's analysis of the CMS Transparency in Coverage Public Use File for the 2024 plan year. We report KFF's published numbers as-is and link each one.
- The marketplace data covers HealthCare.gov (federal-platform) issuers only, so it does not capture every U.S. plan; treat it as a large, representative sample rather than a national census.
- KFF notes the public data lacks a documented reason for a large share of denials ("other"), and that the external-appeal overturn rate is suppressed for small counts — we do not fill those gaps with estimates.
- We do not publish AppealArmor's own outcome numbers. We delete each patient's case 31 days after it starts, so we have no outcome record of our own to report. Every number on this page is KFF's.
How AppealArmor tries to close the gap
AppealArmor is a free tool for patients. You upload or paste your denial letter and check every detail it reads from it. It then drafts an appeal letter that answers the denial and cites the federal appeal rules for your type of plan and, where state insurance law applies to your plan, your state's own law (quoted or summarised), taken from official sources (the eCFR, your state's statutes and regulations, your state insurance regulator, federal agency contacts, and for drugs the FDA label). You get the letter as a Word file and a PDF, plus a Next Steps sheet: where to send it, your deadline as your letter states it, and who to contact if it is denied again.
These are descriptions of the product, not outcome claims. State law is cited only from a checked table of 98 provisions on external review and step therapy for 50 states and the District of Columbia (the letter can cite 92 of them; the rest go on the Next Steps sheet), and only when it applies to your plan (see the list). It does not cite case law.
Sources
- KFF — Claims Denials and Appeals in ACA Marketplace Plans in 2024
CMS Transparency in Coverage Public Use File (2024 plan year) - eCFR — 45 CFR 147.136 (internal claims & appeals and external review)
U.S. federal regulation - HealthCare.gov — External review
U.S. Department of Health & Human Services
This report is free to cite and share under CC BY 4.0 with attribution to AppealArmor. Figures verified against the linked public sources on 2026-07-01.
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