Less Than 1% Of Denied Insurance Claims Get Appealed — But Most Appeals Win. Here's The Data | ICA

1.0 Why This Matters To You

 

If you've ever gotten a denial letter and just... let it go, you're not alone. Ninety-nine out of a hundred people do the exact same thing.

 

What most of them don't know is that the data runs strongly the other way: appeal rates climb toward 80% at the strongest review stage, and even the weakest stage — appealing straight back to the same insurer — wins about one in three times.

 

The gap between "1% appeal" and "up to 80% win" isn't about who has the strongest case. It's mostly about who bothers to ask twice.

 

By the end of this report, you'll know exactly how those odds break down by claim type and appeal stage, why so few people appeal in the first place, and the specific steps that turn a denial letter into a real second chance — plus where to get that help for free if you'd rather not do it alone.

 

 

2.0 Table of Contents

 

1. The Numbers: How Often Denials Get Appealed (And How Often They Win (#the-numbers)

2. Why So Few People Appeal a Denied Claim (#why-so-few)

3. Overturn Rates by Claim Type(#overturn-rates)

4. Common Reasons Claims Get Denied in the First Place (#common-reasons)

5. How to File an Effective Appeal(#how-to-file)

6. When to Get Professional Help With an Appeal(#pro-help)

7. Frequently Asked Questions (#faq)

 

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3. The Numbers: How Often Denials Get Appealed (And How Often They Win)

 

Here's a strange fact buried in U.S. insurance data: denials are common, appeals are rare, and appeals work far more often than most people expect. That gap between the three is where a lot of money and medical care quietly slips away every year.

 

Start with how often claims get denied at all. [KFF's analysis of federal transparency data](https://www.kff.org/patient-consumer-protections/claims-denials-and-appeals-in-aca-marketplace-plans-in-2024/) found that insurers selling ACA marketplace plans on HealthCare.gov denied 19% of in-network claims in 2024 and 37% of out-of-network claims — a combined average of roughly one in five claims denied.

 

Now the appeal rate. Members appealed fewer than 1% of those denied claims. Ninety-nine times out of a hundred, a denial simply ends the conversation.

 

That's where the story usually stops for most readers — and where it should really begin, because the appeal success numbers tell a different story depending on which stage you look at.

 

Internal appeals (asking the same insurer to look again) succeed a modest amount of the time. KFF's marketplace data shows insurers upheld their own denial in 66% of internal appeals — meaning about one in three internal appeals wins. Not a majority, but a free filing with 34% odds is a bet most people would take almost anywhere else in life.

 

External appeals — where an independent reviewer outside the insurance company makes the call — look a lot better. A [research letter published in JAMA Internal Medicine](https://www.healthcaredive.com/news/insurance-denials-overturned-appeal-new-york-study-JAMA/817490/) in April 2026, led by Joseph Dov Bruch, PhD, of the University of Chicago, examined 51,394 closed external appeal cases in New York State between May 2019 and December 2025. Across all cases, 46.7% of denials were overturned. And the trend line matters as much as the average: overturn rates climbed from 38% in 2019 to almost 53% in 2025, while the number of people filing appeals more than doubled over the same period.

 

Medicare Advantage prior authorization appeals show the widest gap between how rarely people appeal and how often it pays off. [KFF's review of CMS data](https://www.kff.org/medicare/medicare-advantage-insurers-made-nearly-53-million-prior-authorization-determinations-in-2024/) found that Medicare Advantage insurers made nearly 53 million prior authorization decisions in 2024 and denied 4.1 million of them, in full or in part. Only 11.5% of those denials were appealed — but of the ones that were, 80.7% were fully or partially overturned. Every year from 2019 through 2024, more than eight in ten appeals in this category succeeded.

 

The most extreme version of this pattern shows up in a June 2026 [HHS Office of Inspector General report](https://oig.hhs.gov/reports/all/2026/medicare-advantage-organizations-overturned-nearly-all-appealed-prior-authorization-denials-for-skilled-nursing-facility-admission-raising-concerns-about-initial-denials/) on skilled nursing facility admissions. Nineteen Medicare Advantage organizations denied 12% of SNF admission requests in June 2024. Enrollees appealed only 18% of those denials — and when they did, plans overturned 95% of them. For denials issued by the contractor naviHealth specifically, the overturn rate hit 97%.

 

As the OIG report put it plainly:

 

"The extremely high overturn rate indicates that some enrollees were initially denied medically necessary care and raises concerns about denials that were not appealed."

 

That's a government watchdog saying, in essence, that a lot of "no" answers were wrong to begin with — and the only people who found that out were the ones who pushed back.

 

So is "most appeals win" the whole truth? Not at every stage — internal appeals succeed a minority of the time. But your odds climb steadily the further you're willing to take it: roughly one in three at internal review, close to one in two at external review, and four in five in Medicare Advantage. What almost never wins is the appeal nobody files.

 

Appeal stage comparison

 

| Appeal stage | Who reviews it | Typical cost | Typical timeline | Overturn rate |

|---|---|---|---|---|

| Internal appeal | The same insurer, different reviewer | Free | 30–60 days (72 hours if expedited) | ~34% |

| External review | Independent third-party reviewer | Usually free (some states cap fees) | Weeks to a few months | 46.7%, rising toward 52.5% |

| Medicare Advantage appeal | Independent review entity (automatic if upheld) | Free | Weeks | 80.7% |

| MA skilled nursing facility appeal | Plan medical review | Free | Weeks | 95%, up to 97% |

 

For a closer look at what each of these levels actually involves, see our guide to [the four levels of an insurance appeal](/appeals/levels-of-appeal-explained/).

 

 

4. Why So Few People Appeal A Denied Claim

 

If appeals work this well, the under-1% appeal rate needs an explanation. A few overlapping reasons come up again and again in the research, and none of them is that people are lazy.

 

Most people don't know the right exists. A January 2026 [KFF poll](https://www.kff.org/public-opinion/kff-health-tracking-poll-prior-authorizations-rank-as-publics-biggest-burden-when-getting-health-care/) found that two-thirds (66%) of insured adults consider delays and denials a "major problem," and a third had personally been denied a service or medication their doctor prescribed in the past two years. Yet in a separate KFF consumer survey, only about 40% of people believed they had a legal right to appeal to a government agency or independent medical expert. Awareness was weakest among marketplace enrollees, who have the most exposure to denials and the least idea what to do about them.

 

Denial letters bury the instructions. ProPublica's reporting documented [cases](https://www.propublica.org/article/health-insurance-denial-external-review) where appeal instructions were tucked away deep in a multi-page denial letter instead of stated up front. Maryland and Connecticut have since passed laws requiring appeal rights to appear in bold print at the top of the letter. After Connecticut's law took effect, more than 40% of referrals to the state's Office of the Healthcare Advocate came from people who'd received the redesigned letters — meaning the information had technically been there all along. It just wasn't findable.

 

People assume it won't work. Among those who did appeal, the [Commonwealth Fund's 2025 Affordability Survey](https://www.commonwealthfund.org/publications/surveys/2026/jun/how-health-insurance-coverage-denials-affect-americans-2025-affordability-survey) found more than half ultimately got somewhere — 30% received the originally recommended care and another 25% got an approved alternative. Among people who challenged a claim denial specifically, 33% had their bill reduced or eliminated. The doubt that keeps most people from trying turns out to be largely unwarranted.

 

Commonwealth Fund president Joseph Betancourt, MD, described what the hesitation costs patients:

 

"In many cases, it leads to delayed care or no care at all; in the worst cases, it puts patients' lives at risk."

 

The people hit hardest have the least energy to fight. Denials cluster around serious, expensive, exhausting situations — the exact circumstances where paperwork stamina runs lowest. A caregiver managing a parent's post-hospital care, or a patient mid-treatment for a serious illness, often has the least bandwidth exactly when the stakes are highest.

 

The system doesn't make it easy to try. ProPublica has also documented cases where members requesting their own claim file — the internal notes an insurer used to justify a denial — received form letters treating the request as a formal appeal instead, which restarts a slower, more complicated clock. Consumer advocates argue this friction isn't accidental. Kathleen Holt, Connecticut's state health care advocate, put it directly in [ProPublica's reporting](https://www.propublica.org/article/health-insurance-denial-external-review):

 

"The insurance companies know that people don't appeal, and in some ways I think they can be more aggressive with their denials."

 

Holt's point, in her own words elsewhere in that reporting, is that insurers don't expect most people to push back — so the rare policyholder who does costs them little in the aggregate.

 

That's one advocate's characterization, not a settled industry-wide fact, and insurers push back on it. The trade group AHIP has said of denial data generally:

 

"The vast majority of denials are due to incorrect or incomplete claim submissions from providers."

 

AHIP's broader statement attributes most denials to duplicate claims, requests for unproven treatments, or services that were never covered in the first place — the industry's own explanation for why the "other" and "administrative" categories run so high.

 

Both things can be part of the picture — some denials are genuinely administrative housekeeping, and some reflect an incentive structure that rewards not appealing. Either way, the practical conclusion for a policyholder is the same: the paperwork gap is worth closing.

 

What the Data Says About Waiting It Out

 

None of this means every appeal wins, or that appealing is free of hassle. It means the odds are better than the 1% appeal rate would suggest, and the biggest single barrier isn't the merits of anyone's case — it's simply not trying.

 

5. Overturn Rates By Claim Type

 

The JAMA Internal Medicine study is useful precisely because it breaks results down by service and diagnosis instead of reporting one blended number. The spread runs from roughly 30% to 78%, which means appealing has real value across categories — just not identical value.

 

Overturn rates by service type (New York external appeals, 2019–2025)

 

| Service category | Overturn rate |

|---|---|

| Home health care services (n=6,469) | 78.4% |

| Surgical services | More than 50% |

| Dental / orthodontic procedures | More than 50% |

| Pharmacy / prescription drugs | More than 50% |

| All categories combined (n=51,394) | 46.7% |

 

Overturn rates by diagnosis

 

| Diagnosis category | Overturn rate |

|---|---|

| Substance use disorder treatment | 61.5% |

| Mental health services | 60.6% |

 

A few limits are worth noting honestly, because a data-driven claim should own its gaps. This dataset comes from one state — New York is unusual in publishing insurer-identified external appeal outcomes at all. Appealed cases also aren't a random sample of every denial; people who appeal may differ systematically from people who don't, and the study's authors say as much. And self-funded employer plans, which cover about 67% of insured workers, don't face the same federal denial-reporting requirements — so a large share of insured Americans simply isn't represented in any of these numbers.

 

Even accounting for that, the pattern holds up well enough to be useful: home health, behavioral health, and substance use denials overturn at rates well above the overall average, which is exactly the kind of category-specific detail that rarely makes it into general "should I appeal" advice.

 

Related reading: [Why "It's Not Medically Necessary" Is Not the Final Word](/common-claim-mistakes/medical-necessity-denials/)

 

 

6. Common Reasons Claims Get Denied In The First Place

 

Understanding why claims get denied changes how a person appeals, and it also reframes the entire problem. According to [KFF's review of 2024 CMS data](https://www.kff.org/patient-consumer-protections/claims-denials-and-appeals-in-aca-marketplace-plans-in-2024/), the top reasons insurers give for in-network denials are:

 

• "Other" (unspecified) reasons — 36%. The largest bucket, and the least transparent. Insurers aren't required to explain further in most cases.
• Administrative reasons — 25%. Things like duplicate claims, missing information, or filing outside a deadline.
• Excluded service — 13%. The billed service was never part of the policy's covered benefits to begin with.
• Lack of prior authorization or referral — 9%. The service happened before the insurer signed off on it.
• Lack of medical necessity — 5%. The clinical dispute people usually picture when they think "denied claim."

 

Denial reasons and what they mean for your odds

 

| Reason cited | Share of denials | What it usually takes to fix |

|---|---|---|

| Other / unspecified | 36% | Request the claim file to find out what actually happened |

| Administrative error | 25% | Correct the paperwork, resubmit, or point out the mistake |

| Excluded service | 13% | Check the policy language; sometimes miscoded as excluded when it isn't |

| No prior authorization | 9% | Retroactive authorization request or peer-to-peer review |

| Medical necessity | 5% | Doctor's letter, clinical records, sometimes external review |

 

That last row is the most important thing in this section. Most people picture an appeal as a fight over whether their care was medically justified. In reality, only about one in twenty denials is coded that way. The rest are administrative, coverage-scope, or unexplained — meaning the large majority of denials reflect a paperwork or coverage-terms problem someone can fix, not a clinical argument someone has to win.

 

Why "Medical Necessity" Denials Are the Minority

 

This matters for a practical reason: external review, the stage with the strongest odds, is largely reserved for medical-judgment disputes. Because that category is a small share of all denials, many policyholders never reach the highest-success channel at all — which makes getting the internal appeal right, or simply fixing the paperwork, the more common path back to coverage.

 

 

7. How To File An Effective Appeal

 

Filing an appeal moves a case out of an automated first pass and into an actual review. The process has a rhythm to it, even though the specifics vary by plan type and state.

 

• Step 1: Request your claim file. Before writing anything, ask your insurer for the notes and documentation used to deny you. ProPublica's [Claim File Helper](https://projects.propublica.org/claimfile/) offers a free template for exactly this request. Under ERISA, most insurers must respond within 30 days. 
• Step 2: File the internal appeal. By law, the reviewer must be someone who wasn't involved in the original denial — often a different medical professional entirely. Keep it factual: what was denied, why you believe it was wrong, and what documentation supports that.
• Step 3: Escalate to external review if the internal appeal fails. This is where an independent reviewer outside the insurance company takes over. Deadlines here are unforgiving — often around four months from the final internal denial — so mark the date the moment you get that letter.
• Step 4: Document everything as you go. Keep copies of every letter, note the date and name of every phone call, and hold onto records your doctor sends on your behalf. A denial letter that arrives on page seven with the appeal instructions buried at the bottom is still a valid denial letter — the paperwork burden is on you to find and use it, unfortunately, even where it should be easier.

 

7.10 What to Include in Your Appeal Letter

 

A strong appeal letter typically covers:

1. The claim number and date of service
2. A clear statement of what's being appealed and why
3. Supporting documentation (doctor's notes, test results, treatment guidelines)
4. A specific request — what outcome you're asking for
5. Any relevant policy language that supports coverage

 

Step-by-step appeal timeline

 

| Stage | Deadline to act | What happens |

|---|---|---|

| Request claim file | Anytime after denial | Insurer must respond, typically within 30 days |

| Internal appeal | Usually within 180 days of denial | Insurer re-reviews with a new decision-maker |

| Internal appeal decision | 30–60 days standard; 72 hours if expedited | Insurer upholds or reverses |

| External review request | Typically within 4 months of final internal denial | Independent reviewer takes the case |

| External review decision | Weeks, faster if expedited | Binding on the insurer in most states |

 

Standard reviews move at a bureaucratic pace. If your situation is urgent — an active treatment being delayed, for instance — ask specifically for an expedited review, which can be resolved in as little as 72 hours.

 

8. When To Get Professional Help With An Appeal

 

Not every appeal needs outside help, but some situations benefit from it — particularly complex denials, high dollar amounts, or cases involving an ongoing serious illness.

 

Free consumer assistance programs exist in most states and are consistently under-used relative to how effective they are. These state-run or state-funded offices help residents navigate denials and appeals at no cost, and in some states they resolve a large share of the cases they take on in the consumer's favor. As Elisabeth Benjamin of New York's Community Service Society described the work to ProPublica:

 

"We write appeals for them, sometimes going through thousands of pages of medical records and writing 15- to 20-page appeals."

 

That's the kind of labor most people can't take on alone while also managing a health crisis — which is exactly what these programs exist for.

 

Paid patient advocates or attorneys make more sense for high-dollar, high-complexity, or repeatedly denied claims, particularly disability claims or self-funded ERISA employer plans, where the appeal rules differ from state-regulated insurance and free consumer assistance programs may have less jurisdiction.

 

A quick way to decide which lane fits:

 

If your situation involves:

• A denial under $1,000 with a clear paperwork error → Try the internal appeal yourself first.
• A complex or recurring denial, but no attorney needed yet → Contact your state's free consumer assistance program.
• A high-dollar, ERISA, or long-term disability denial → Consider a patient advocate or attorney with relevant experience.

 

If you're not sure where your denial falls, a free consumer assistance program is usually the right first call — they can tell you whether your case needs more than what they offer.

 

Explore free help: every state's consumer assistance directory works a little differently — [find your state's free consumer assistance program](/resources/consumer-assistance-directory/) to see what's available before paying for help you might not need.

 

9. Frequently Asked Questions

1. Does It Cost Money To Appeal A Denied Insurance Claim?

Internal appeals are free. External reviews are free or low-cost in most states—some cap the fee at around $25, and several states, including Connecticut, have eliminated the fee entirely.

2. How Long Does An Insurance Appeal Take?

Standard internal reviews typically take 30–60 days. Expedited reviews for urgent situations can be resolved in as little as 72 hours. External review timelines vary by state but generally range from a few weeks to several months.

3. Is My Denial Likely To Be Overturned?

It depends on the reason for the denial and the stage of appeal. Administrative and paperwork-related denials—about 61% of all denials combined—are often the easiest to correct. In New York's external review data, overturn rates ranged from roughly 30% to 78% depending on the service, while Medicare Advantage appeals overturn at more than 80%. Your own state's or plan's results may differ.

4. Will Appealing Make My Insurer Angry Or Hurt Future Claims?

No evidence from the available research suggests that filing a lawful appeal affects future coverage decisions. Appeals are a legal right provided under insurance regulations, not a privilege insurers can hold against you.

5. Can An Insurance Company Ignore An External Review Decision?

No. In most states, an external review decision is binding on the insurer once it is issued. This is one of the reasons external review is considered the strongest stage of appeal for disputes involving medical judgment.

This article is educational information, not legal, medical, or financial advice. Coverage rules, deadlines, and appeal rights vary by plan type and by state.

 

Editorial Disclaimer: This report is provided for educational and informational purposes only. It is not legal, financial, insurance, or tax advice. Insurance laws, policy terms, and claim outcomes vary based on individual circumstances and jurisdiction. Readers should review their own insurance policies and consult qualified professionals for advice specific to their situation.