Insurance Denial Rates by Insurer (2026)" class="auto-link">Denial Rates in 2025: What the Data Shows

If your health insurance claim was recently denied, you are far from alone. Denial rates have been climbing steadily for years, and 2025 data paints a troubling picture for American consumers. Understanding the scope of the problem -- and the data behind it -- is the first step toward fighting back effectively.

This article breaks down the latest denial rate statistics, explains what is driving the trend, and gives you actionable steps to protect yourself.

The Big Picture: How Often Are Claims Denied?

The numbers are staggering. According to a 2024 KFF analysis of ACA marketplace plans, major insurers denied approximately 17% of in-network claims on average in 2023 -- the most recent year with complete data. Some insurers denied more than 20% of all claims submitted.

That translates to roughly 50 million denied claims per year across the individual marketplace alone. When you include employer-sponsored plans, Medicare Advantage, and Medicaid managed care, the total number of denied claims annually in the United States likely exceeds 200 million.

A ProPublica investigation into UnitedHealthcare found that one of the company's automated systems was rejecting claims with a 90% error rate -- meaning the vast majority of those denials were incorrect. The company continued using the system because so few patients appealed.

Denial Rates by Major Insurer

Not all insurers deny claims at the same rate. KFF data from ACA marketplace plans shows significant variation:

These numbers represent in-network claims only. Out-of-network denial rates are substantially higher, often exceeding 30-40% depending on the insurer and service type.

It is worth noting that Kaiser Permanente's lower denial rate is partly attributable to its integrated model, where the insurer and provider are the same organization. For traditional insurers where claims processing is separate from care delivery, the friction between provider and payer creates more opportunities for denials.

What Types of Claims Get Denied Most?

The reason for denial matters enormously for your appeal strategy. According to data compiled from state insurance departments and CMS reporting:

• Administrative/technical denials (30-40%): Missing information, coding errors, Prior Authorization Denied: How to Appeal" class="auto-link">prior authorization failures, filing deadline issues. These are often the easiest to overturn on appeal.
• Medical necessity denials (25-30%): The insurer's reviewer determined the treatment was not medically necessary. These require clinical evidence to overturn.
• Out-of-network/benefit exclusion denials (15-20%): The provider or service was not covered under the plan terms. Understanding the No Surprises Act is critical here.
• Prior authorization denials (10-15%): Treatment was not pre-approved as required.
• Experimental/investigational denials (5-10%): The insurer classified the treatment as experimental. These are among the hardest to overturn but not impossible.

The Appeal Gap: Why Most Denials Go Unchallenged

Perhaps the most disturbing statistic in all of health insurance is the appeal rate. According to KFF, fewer than 0.2% of denied claims -- roughly 1 in 500 -- are appealed by patients. This means insurers face essentially zero accountability for the vast majority of their denials.

Why don't people appeal? The reasons are predictable:

1. They don't know they can. Many consumers are unaware of their ACA appeal rights or ERISA protections.
2. The process seems too complicated. Insurance appeal procedures are deliberately opaque.
3. They assume they will lose. In reality, 40-60% of external appeals result in the denial being overturned.
4. They give up and pay out of pocket. This is exactly what insurers are counting on.

The data on appeal success rates tells a very different story from what most consumers expect. When patients do appeal, the results are surprisingly favorable:

• Internal appeal success rate: 30-50%, depending on insurer and denial type (Commonwealth Fund, 2023)
• External Independent Review: Complete Guide" class="auto-link">external review success rate: 40-60%, with some states reporting even higher overturn rates (NAIC data)
• medical necessity denials overturned on external review: Up to 70% in some categories

These numbers make it clear: the system is designed to discourage appeals, not because denials are correct, but because low appeal rates save insurers billions of dollars annually.

The Role of Automation and AI in Denials

A growing factor in rising denial rates is the use of automated systems and artificial intelligence by insurers. A 2023 STAT News investigation revealed that major insurers including Cigna were using automated systems to deny claims in bulk -- with physicians spending an average of 1.2 seconds reviewing each case before the system issued a denial.

UnitedHealthcare's use of the naviHealth algorithm to deny post-acute care claims became the subject of a federal class-action lawsuit in 2023. The algorithm was reportedly overriding the clinical judgment of treating physicians, leading to patients being discharged from rehabilitation facilities before they had recovered.

The use of AI in insurance is a double-edged sword. While it can speed up legitimate claims processing, it also enables mass denials at a scale that was previously impossible.

Trends Driving Higher Denial Rates in 2025

Several factors are converging to push denial rates higher:

1. Insurer profitability pressure: Publicly traded insurers face Wall Street expectations for quarterly earnings growth. Denying more claims is a direct path to higher margins.
2. Increased prior authorization requirements: The American Medical Association reports that prior authorization requirements have expanded significantly, creating more opportunities for denials.
3. Automated denial systems: AI and algorithmic systems enable insurers to process -- and deny -- claims faster than ever.
4. Staffing shortages at insurers: Fewer human reviewers means more reliance on automated systems that default to denial.
5. Post-pandemic utilization increases: As patients seek care deferred during COVID-19, insurers are pushing back on the surge in claims volume.

What You Can Do: Actionable Steps

Understanding the data is empowering, but action is what gets your claim paid. Here is what you should do:

1. Always Appeal

Given the 40-60% success rate on external review, there is almost no reason not to appeal a denial. The worst outcome is that the denial stands -- which is where you already are. Learn how to write an effective appeal letter.

2. Request Your Complete Claim File

Under ERISA and the ACA, you have the right to request your complete claim file, including the insurer's internal criteria, reviewer notes, and clinical guidelines used to deny your claim. This information is essential for building your appeal.

3. Understand Your Specific Denial Reason

Read your denial letter carefully. The denial reason code and explanation dictate your appeal strategy. An administrative denial requires different evidence than a medical necessity denial.

4. Know Your Deadlines

Most plans give you 180 days from the denial to file an internal appeal, but some have shorter windows. Check your EOB)" class="auto-link">Explanation of Benefits and plan documents immediately after receiving a denial.

5. File Regulatory Complaints When Appropriate

If your insurer is acting in bad faith -- delaying responses, ignoring appeals, or misrepresenting your benefits -- file a complaint with your state insurance commissioner. Regulatory pressure can be remarkably effective.

6. Use External Review

If your internal appeal is denied, you almost always have the right to an external review by an independent third party. This is where the 40-60% overturn rate applies. Do not skip this step.

The Bottom Line

Insurance denial rates in 2025 are high, rising, and disproportionately affecting consumers who do not fight back. The data overwhelmingly shows that appealing works -- but only if you actually do it. The system relies on your silence.

The most important thing you can do is appeal every denial that you believe is wrong. Armed with the right data, the right structure, and the right evidence, your odds are far better than most people realize.

Ready to fight your denial? ClaimBack generates professional, evidence-backed appeal letters in minutes. Our AI analyzes your denial reason and builds a customized appeal using the legal frameworks and clinical arguments most likely to succeed -- Start Your Free Appeal.

Disclaimer: ClaimBack provides AI-generated appeal assistance for informational purposes only. ClaimBack is not a law firm and does not provide legal advice. Statistics cited reflect the most recent available data and may vary by plan type and state.

Denied a claim? The data says you should fight it. ClaimBack helps -- Start Free

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