The Worst Health Insurance Companies for Claims: Denial Data Compared

Not all health insurers are created equal when it comes to paying claims. Some companies approve the vast majority of submitted claims with minimal friction. Others deny aggressively, rely on algorithmic review, and make the appeal process as difficult as possible. Here's an honest look at which insurers have earned the worst reputations for claim handling — and what the data says.

How We Evaluate "Worst" for Claims

Several objective data sources paint a picture of insurer behavior:

• ACA marketplace Denial Rates by Insurer (2026)" class="auto-link">denial rates (reported to CMS): The percentage of in-network claims denied by each insurer
• NAIC complaint ratios: Consumer complaints per 1,000 covered lives, benchmarked against the national median
• State external appeal overturn rates: How often independent reviewers overturn insurer denials
• Regulatory actions and settlements: Fines, consent orders, and class-action outcomes
• Congressional and OIG investigations: Federal scrutiny of specific practices

No single metric tells the complete story, but combined, they reveal consistent patterns.

The Insurers with the Worst Claims Records

1. UnitedHealthcare

UnitedHealthcare is the largest health insurer in the United States by revenue — and one of the most frequently criticized for claim handling. A 2023 congressional investigation found that UHC's Medicare Advantage subsidiary denied post-acute care claims at a 90% rate, far above industry averages. The same investigation found that many of those denials were reversed when patients appealed.

UHC's NAIC complaint ratio consistently runs above the national median. The company was also the subject of a 2024 Senate investigation into its use of AI to deny claims, which found that UHC's algorithm denied claims at a rate 11 times higher than industry peers in some categories.

2. Cigna

Cigna's 2023 ProPublica investigation revealed a disturbing practice: medical reviewers were rejecting claims in bulk, reviewing hundreds of cases per day without reading individual patient files. The company reached a $172 million multi-state settlement in 2024 related to these practices.

Cigna's behavioral health denial record is particularly poor. Multiple state investigations have found that Cigna applies more restrictive criteria to mental health and substance use disorder claims than to medical/surgical claims — a violation of federal parity law.

3. Molina Healthcare

Molina primarily serves Medicaid and ACA marketplace enrollees. While its premium prices are competitive, Molina has faced regulatory sanctions in multiple states for excessive claim denials and inadequate provider networks. State Medicaid agencies in California, Washington, and Ohio have taken enforcement action against Molina for denial practices that violated state contracts.

4. Centene (and Subsidiaries)

Centene, which operates under brand names including Ambetter, WellCare, and others, has settled numerous state-level investigations related to claim denials, improper billing, and network adequacy failures. A 2022 multi-state settlement involving Centene's pharmacy benefit practices resulted in a $1.1 billion payout. Ambetter exchange plans consistently appear in the top quintile for ACA denial rates.

5. Oscar Health

Oscar targets tech-savvy individual market consumers with a simple digital interface — but its claims handling has drawn significant criticism. Oscar's narrow networks and heavy reliance on Prior Authorization Denied: How to Appeal" class="auto-link">prior authorization have led to above-average denial rates, particularly for out-of-network emergency care and specialist visits.

What High Denial Rates Actually Mean for You

A high denial rate doesn't mean every claim will be denied. But it does mean you should:

• Never assume approval: Get prior authorization for everything that requires it, and keep documentation.
• Keep records of everything: Every conversation, every denial letter, every authorization number. You'll need this for your appeal.
• Understand your appeal rights immediately: The denial letter should include the reason for denial and instructions for appeal. Read it immediately and calendar your appeal deadline.
• Don't accept denials passively: Appeal data consistently shows that a large percentage of denials are overturned when patients push back.

The Insurers That Perform Better

For comparison: Blue Cross Blue Shield plans (particularly in states with strong regulatory environments), Kaiser Permanente, and some regional non-profit insurers consistently show lower complaint ratios and lower ACA denial rates. If you have the option to choose among insurers, checking NAIC complaint ratios and state-specific denial rate data is worth the time.

Fight Back With ClaimBack

If your insurer has wrongly denied your claim, you don't have to accept it. ClaimBack helps you build a professional, evidence-driven appeal that addresses your insurer's specific denial reasons. Start fighting back today at https://claimback.app/appeal.

Related Reading

• Common Reasons Insurance Claims Are Denied
• Internal vs. External Insurance Appeals
• How to Write an Insurance Appeal Letter