Health Insurance Denial Rates by Carrier 2026

That sentence should make you angry, because it describes a system where the same appendectomy, the same MRI, the same emergency room visit gets paid or denied depending on which company's logo is on your card. The data behind it isn't anecdotal. It's federal.

Under the Affordable Care Act, insurers selling qualified health plans on HealthCare.gov must report their in-network claims denial rates to the Centers for Medicare & Medicaid Services every year, in the Transparency in Coverage public use file. KFF — the independent health policy research organization — analyzes that file annually, and its analysis of plan year 2024 data is the clearest picture available of which companies say no most often.

The National Baseline: One in Five Claims Denied

Across HealthCare.gov states in 2024, marketplace insurers denied 19.1% of in-network claims — roughly 8.8 million rejected claims out of 46 million submitted. Out-of-network claims fared worse at 37%, for a combined average of 20%.

That 19.1% figure was actually an improvement — down 3.4 points from 22.5% in 2023, the largest single-year drop on record. But context matters: it remains above the 16.7% recorded in 2021, and one in five is not a number any other industry would tolerate for a product people are legally required to buy.

The range is what should hold your attention. In-network denial rates ran from 3% at the best-performing insurers to 36% at the worst. Three percent of reporting insurers denied 30% or more of in-network claims — down from 17% the year before, but still: a meaningful slice of the market rejects nearly a third of what its members submit.

The Carrier Rankings

Among major national insurers, the spread is stark. Oscar Health denied 25.3% of in-network claims — the highest rate among large marketplace carriers. Molina Healthcare denied 22%. UnitedHealthcare, processing a staggering 6.4 million claims, cut its rate from 34.2% to 19.1% in a single year, a fifteen-point improvement that proves these numbers can move when a company decides to move them. Kaiser Permanente sits at the other end at roughly 6%, a denial rate one-quarter of Oscar's.

"Your insurance card is a promise. The denial rate is the receipt for how often it's kept." When you compare carriers, you are comparing how seriously they take that promise.

Geography matters nearly as much as the carrier. Hawaii led all states at 26.9%; Alaska followed at 25.5%. South Dakota had the lowest rate at 5.4%. Your odds of getting paid depend on your ZIP code in ways no actuary will explain to you at enrollment.

Why Claims Get Denied — and Why Almost Nobody Fights Back

The denial reasons insurers report are revealing. The most common category in 2024 was simply "Other" — reason not listed — at 36%. Administrative reasons accounted for 25%. Lack of prior authorization or referral: 9%. Lack of medical necessity: 5%. Read that again: the clinical judgment you might expect to drive denials — whether the care was actually needed — explains one in twenty rejections. The rest is paperwork, plan design, and a category the insurer couldn't be bothered to name.

And here's the statistic that should end every conversation about whether denials are legitimate: fewer than 1% of denied claims are ever appealed. Consumers accept the rejection as final. But of the internal appeals that are filed, insurers uphold their own decision 66% of the time — meaning a third are overturned. Marketplace enrollees filed at least 5,881 external appeals in 2024, just 4% of upheld internal appeals. The system counts on your silence, and the data shows it gets it.

What the Numbers Don't Tell You

Every dataset has blind spots, and this one has large ones. The CMS Transparency in Coverage file covers qualified health plans on the federally facilitated marketplace only. It excludes the roughly 150 million Americans on employer-sponsored plans, the state-run exchanges like California's Covered California and New York's marketplace, Medicaid managed care, and Medicare Advantage — each of which runs its own denial machinery under different reporting rules. If your coverage comes through your job, these exact rankings don't apply to your carrier's group business, though the corporate culture behind the numbers travels.

The data is also aggregated in ways that limit what you can learn. Insurers report denial rates across all items and services combined, with no breakdown by service type — you can't see whether a carrier denies MRIs more than physical therapy. They report percentages, not raw claim volumes, which complicates comparisons between a giant like UnitedHealthcare and a regional plan. And the "reasons" data is thin: more than a third of denials sit in an "Other" bucket the insurer never explained.

None of that diminishes the file's value. It remains the only apples-to-apples, federally mandated, insurer-level denial comparison in the country. Use it the way it was designed to be used: at open enrollment, when you're choosing between carriers in your state, with the full knowledge that the cheapest premium sometimes comes with the most expensive claims department.