Which health insurers deny the most claims? We ranked the top 10 US insurers by denial rate, appeal success rate, and average resolution time.
Ranked by claim denial rate (highest to lowest). Industry average: 14.2%.
| Rank | Insurer | Denial Rate | Members | Appeal Success | Avg Days |
|---|---|---|---|---|---|
| #1 | Centene/Ambetter | 21.2% | 26M | 52% | 34d |
| #2 | Molina Healthcare | 18.3% | 5M | 48% | 38d |
| #3 | Aetna/CVS Health | 17.2% | 22M | 55% | 28d |
| #4 | Anthem/Elevance | 17.1% | 46M | 54% | 30d |
| #5 | Cigna/Evernorth | 16.9% | 14M | 57% | 26d |
| #6 | UnitedHealthcare | 16.1% | 49M | 53% | 32d |
| #7 | Oscar Health | 15.8% | 1.5M | 51% | 29d |
| #8 | Humana | 14.5% | 17M | 58% | 27d |
| #9 | Blue Cross Blue Shield | 12.8% | 115M | 61% | 25d |
| #10 | Kaiser Permanente | 6.2% | 12.5M | 68% | 18d |
Data sourced from CMS Transparency in Coverage filings and state insurance department reports. Denial rates represent in-network claims on ACA marketplace plans. Appeal success rates are estimates based on publicly reported data.
Breakdown of the most common denial reasons across all insurers.
Identify the exact reason code and policy provision cited. This tells you exactly what to counter in your appeal.
Use our free denial rate checker to see how often your insurer denies claims like yours.
Calculate your exact appeal deadline based on your plan type and state. Missing the deadline forfeits your right to appeal.
ClaimBack writes a professional appeal letter citing the specific laws and clinical criteria for your situation — in 3 minutes.
According to CMS Transparency in Coverage data for ACA marketplace plans, Centene/Ambetter has the highest denial rate at 21.2%, followed by Molina Healthcare at 18.3% and Aetna/CVS Health at 17.2%. The industry average across all ACA marketplace insurers is 14.2%.
The average claim denial rate across ACA marketplace health insurance plans is 14.2%, based on CMS Transparency in Coverage data. This means approximately 1 in 7 claims is denied. Rates vary significantly by insurer, from 6.2% (Kaiser Permanente) to 21.2% (Centene/Ambetter).
On average, approximately 55% of properly filed insurance appeals are successful. Success rates vary by insurer: Kaiser Permanente appeals succeed about 68% of the time, while Molina Healthcare appeals succeed about 48% of the time. The key factor is the quality of documentation and legal citations in the appeal letter.
The most common reason for health insurance claim denial is "not medically necessary," accounting for approximately 32% of all denials. This is followed by out-of-network provider (18%), prior authorization required (16%), and not a covered benefit (12%). Many "not medically necessary" denials can be overturned with proper documentation from your treating physician.
Over half of properly filed appeals succeed. ClaimBack writes your professional appeal letter citing the specific laws and clinical standards that apply to your case.
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Denial rates are calculated from CMS Transparency in Coverage data for ACA marketplace plans. We use the most recent annual filings available. "Denial rate" refers to the percentage of in-network claims that were denied, including both pre-service and post-service denials. Appeal success rates are estimated from publicly available data including CMS reports, state insurance department annual reports, and insurer transparency disclosures. Individual results may vary based on the specific denial reason, clinical documentation, and appeal quality.
ClaimBack provides AI-assisted document drafting. We are not a law firm and do not provide legal advice.