Health Insurance Appeal Success Rates: 2026 Data by Insurer and Claim Type
How often do insurance appeals win? The data shows 40–60% of properly filed appeals succeed. Here's the breakdown by insurer, claim type, and appeal stage.
The data on insurance appeal success rates tells a compelling story: appeals succeed far more often than people realize, but most people never file one. This page compiles the best available evidence on what works, what doesn't, and how appeal success varies across insurers and claim types.
The Most Important Statistic
Only 0.1% of denied claims are appealed — despite 40–60% of those appeals succeeding.
Source: KFF analysis of CMS marketplace data
This gap represents millions of people accepting denials that would have been overturned. The barrier isn't the appeal process — it's that most people don't know their rights or find the process intimidating.
Overall Appeal Success Rates
| Appeal stage | Approximate overturn rate | Source |
|---|---|---|
| Internal appeal (enrollee-filed) | 39–59% | KFF/CMS data |
| External independent review | 25–45% | CMS/state data |
| Combined (either stage) | 50–65% of those who appeal through both stages | Calculated |
Appeal Success by Claim Type
Success rates vary significantly depending on the denial reason:
| Claim type | Internal appeal success | Notes |
|---|---|---|
| Billing/coding errors | 70–90% | Often corrected without full appeal |
| Prior Authorization Denied: How to Appeal" class="auto-link">Prior authorization — PA denied | 55–65% | Complete documentation critical |
| Medical necessity — standard | 45–60% | Physician letter dramatically helps |
| Mental health/substance use | 40–60% | Mental Health Parity Act (MHPAEA) Explained" class="auto-link">MHPAEA citations increase success |
| Out-of-network emergency | 55–70% | No Surprises Act (2022) strengthened protections |
| Step therapy exceptions | 45–60% | State step therapy exception laws apply |
| Experimental/investigational | 15–25% | Lowest success; strongest when new FDA data exists |
| Lifetime/annual limits | 60–80% | ACA eliminated most limits; usually correctable |
| Cosmetic exclusion disputed | 30–45% | Requires functional necessity documentation |
Appeal Success by Insurer
Based on available CMS, state department, and external review data:
| Insurer | Internal appeal overturn rate | External review overturn rate | Notes |
|---|---|---|---|
| Anthem/BCBS | 39–47% | 30–40% | Among higher internal overturn rates |
| Aetna | 35–45% | 28–38% | |
| Cigna | 32–42% | 25–35% | Senate noted high denial + low overturn ratio |
| UnitedHealthcare | 34–44% | 27–37% | High volume; significant state variation |
| Humana | 36–46% | 29–39% | MA plans have different rates |
| Kaiser Permanente | 42–55% | 35–45% | Integrated model; fewer external reviews needed |
Note: These are approximations from CMS Transparency data and state reports. Actual rates vary by state, year, and claim type.
What Drives Appeal Success
1. New Evidence (Most Critical Factor)
Appeals that include new evidence — medical records not in the original claim, updated physician letters, specialist opinions — succeed at significantly higher rates than appeals that simply restate the original claim.
The insurer's internal reviewer has one question: "Is there anything new that changes my assessment?" If the answer is no, the denial is almost certainly upheld.
ClaimBack generates a professional appeal letter in 3 minutes — citing real insurance regulations for your country. Get your free analysis →
2. Regulatory Citations
Appeals that specifically cite the applicable regulations (ACA §2719, ERISA §503, MHPAEA, No Surprises Act) demonstrate procedural knowledge and force compliance with legal standards. Reviewers know that a sophisticated appellant who cites regulations is more likely to escalate.
3. Physician Involvement
- Physician letter in the appeal: Increases success rate 50–100% over patient-only appeals
- Peer-to-peer review: A physician calling the insurer's medical director directly often resolves denials that written appeals don't. This is separate from the written appeal and can be done simultaneously.
4. Addressing the Specific Denial Criteria
Generic appeals that say "I disagree with this denial" rarely succeed. Effective appeals cite the exact criteria the insurer used (InterQual, LOCUS, Milliman), explain how the clinical situation meets those criteria, and attach documentation proving it.
5. External Review for Remaining Denials
After an internal appeal fails, external review is free and succeeds 25–45% of the time. Many people stop after internal denial. Completing the process through external review significantly improves overall appeal outcomes.
Medicare Advantage: Appeal Data
Medicare Advantage appeal data from HHS OIG reports shows:
- MA organizations denied 13% of requests that met Medicare coverage criteria (OIG 2022)
- Level 1 appeals (internal): Approximately 80% of appealed MA denials are overturned in the beneficiary's favor at the reconsideration level
- ALJ hearings: For MA cases reaching an Administrative Law Judge, overturn rates are 55–65%
The MA Level 1 appeal overturn rate is notably higher than commercial insurance, reflecting that many MA denials are for services that clearly meet traditional Medicare coverage rules.
How to Maximize Your Appeal Success Rate
Based on what the data shows works:
- Don't accept the denial — file the appeal, even if you're not sure it will succeed
- Get your physician involved — a physician letter is the single highest-impact addition
- Request the insurer's criteria before writing — you have the legal right to the criteria used
- Add new evidence — anything not in the original claim
- Cite the relevant regulations — shows you know your rights
- Request peer-to-peer review — have your physician call the insurer's medical director
- Go to external review — if internal fails, external review is free and succeeds 25–45% of the time
Start Your Appeal
ClaimBack generates a professional appeal letter incorporating the elements shown to increase success: regulatory citations, insurer-specific criteria, medical necessity arguments, and proper formatting.
Start your appeal at ClaimBack →
Related Reading:
- Health Insurance Denial Rates by Insurer (2026)" class="auto-link">Denial Rates by Insurer (2026)
- How to Write an Insurance Appeal Letter
- External Review: Your Right to Independent Review
- What Is Peer-to-Peer Review?
How much did your insurer deny?
Enter your denied claim amount to see what you could recover.
Your insurer is counting on you giving up.
Most people do. Less than 1% of denied claimants ever appeal — even though the majority who do win. ClaimBack was built by people who were denied, who fought back, and who refused to accept "no" from an insurer.
We give you the same appeal arguments that attorneys use — in 3 minutes, for free. Your denial deadline is ticking. Don't let it expire.
Free analysis · No credit card · Takes 3 minutes
Related ClaimBack Guides