Which Health Insurance Company Denies the Most Claims?

If you have ever had a claim denied and wondered whether your insurer is worse than average, you are not imagining things. Denial Rates by Insurer (2026)" class="auto-link">Denial rates vary significantly across major insurers, and federal data reveals some striking patterns. Understanding where your insurer stands can help you recognize when a denial is likely wrongful and push back accordingly.

The Data: What CMS and KFF Tell Us

The Centers for Medicare and Medicaid Services (CMS) requires insurers selling plans on the ACA marketplace to report denial data annually. The Kaiser Family Foundation (KFF) has analyzed this data extensively. Their findings show that across all marketplace plans, insurers denied about 17% of in-network claims on average in 2021. But averages obscure enormous variation.

According to CMS data analyzed by KFF, UnitedHealthcare denied approximately 32% of claims in 2022 across its marketplace plans — one of the highest rates among major insurers. This figure drew significant congressional attention and was cited in the Senate HELP Committee's 2024 investigation into UHC's use of algorithmic denial tools.

Cigna's denial rate hovered around 25% in the same period. Aetna came in at roughly 22–24%. BCBS entities varied widely because BCBS is a federation of regional plans rather than a single national insurer — some BCBS affiliates had denial rates under 10% while others exceeded 25%. Humana's marketplace plan denial rates averaged around 14–16%, somewhat below the industry average, though its Medicare Advantage denial practices have drawn separate scrutiny.

Why UHC's Rate Is So High

UnitedHealthcare has been at the center of several investigations into automated claim denial. The insurer deployed a proprietary algorithm called nH Predict (later NaviMedix) to make Prior Authorization Denied: How to Appeal" class="auto-link">prior authorization decisions for post-acute care. Investigative reporting by ProPublica and STAT News revealed that the algorithm was set to deny claims at a rate far exceeding what the company's own doctors recommended. Class action lawsuits followed.

In 2024, a federal court found that UHC had wrongfully denied post-acute care claims using the nH Predict algorithm, violating ERISA fiduciary duties. The company has faced billions in potential liability across multiple states.

Cigna: Mass Denial Without Review

Cigna faced its own algorithmic scandal. An investigation by ProPublica published in 2023 found that Cigna physicians were reviewing and rejecting claims in bulk — sometimes hundreds of cases per hour — using a system called PxDX (Payer-to-Diagnostics). The system flagged claims automatically, and doctors clicked to deny without opening individual files.

This practice was later cited in congressional testimony and contributed to multiple state insurance department investigations. Cigna ultimately reached settlements in several states.

BCBS: Variation Across a Federation

Blue Cross Blue Shield is not a single company. It is a federation of 33 independent regional plans licensed to use the Blue Cross and Blue Shield trademarks. This means denial rates, appeal policies, and claims handling practices vary significantly by state and plan. Anthem (now Elevance Health) operates BCBS plans in 14 states and has been cited in litigation involving prior authorization denials for mental health and substance use disorder treatment.

Consumers with BCBS should check the specific subsidiary handling their plan, as practices in California (Anthem), Texas (BCBS Texas), and New York (Excellus) differ substantially.

Humana's Medicare Advantage Problem

While Humana's commercial marketplace denial rates appear moderate, the company's Medicare Advantage division has been a target of Office of Inspector General (OIG) audits. A 2023 OIG report found that Medicare Advantage organizations, including Humana, denied prior authorization requests that met Medicare coverage criteria at rates far higher than original Medicare would. Humana's MA denial rate for prior auth requests exceeded 18% in the audited sample, with the OIG concluding that a significant portion of those denials were improper.

How to Appeal Regardless of Your Insurer

Every insurer, regardless of its denial rate, is required to provide an internal appeal process under the ACA and ERISA. For marketplace and employer plans, you have the right to:

• An internal appeal reviewed by a different decision-maker than the original denier
• An expedited appeal (72 hours) for urgent care situations
• An external appeal reviewed by an independent organization after the internal process is exhausted

State insurance commissioners also accept complaints against insurers, and patterns of improper denials can trigger market conduct examinations. If your claim involves Medicare Advantage, you have additional rights through the Medicare appeals process including ALJ hearings and judicial review.

The single most important thing you can do after a denial is request the specific clinical criteria used to make the decision. Insurers are required to disclose this, and it forms the foundation of any successful appeal.

Fight Back With ClaimBack

Whether your insurer denies 10% or 32% of claims, you have the legal right to challenge every denial. ClaimBack helps you build a complete appeal — including the clinical justification, the regulatory citations, and the procedural arguments that insurers often fail to address. Our appeal templates are built from the same frameworks that patient advocates and healthcare attorneys use.

Knowing that your insurer has a documented history of algorithmic or bulk denials can actually strengthen your appeal. It signals to reviewers that the denial may have been automated rather than individualized — and courts and regulators have consistently held that insurers must provide individualized review for each claim.

Start My Free Appeal →

Related Reading

• How to Write an Insurance Appeal Letter
• What Is Medical Necessity?
• Common Reasons Insurance Claims Are Denied