Statistics

Numbers about denials and appeals are easy to misread. Each one here is stated exactly as its source gives it, with the year, who it covers, and what it does not show. None of them predicts what will happen in your case.

We do not combine or round figures from different sources. When two numbers sound alike but come from different programs or years, they are listed separately.

HealthCare.gov marketplace insurers denied 19% of in-network claims in plan year 2024.

19% of in-network claims denied (about 85 million of about 451 million claims) (2024 plan year)

Who it covers: Insurers selling marketplace plans on HealthCare.gov (not state-run marketplaces), as reported to the Centers for Medicare & Medicaid Services. Claims for care already received; prior authorization requests are not included.
Source: KFF, Claims Denials and Appeals in ACA Marketplace Plans in 2024 (24 March 2026)
What it does not show: Denial rates by insurer ranged from 3% to 36%, so your insurer may be far from the average. Claims that were denied and later resubmitted and paid are not counted as denied. The figure says nothing about employer plans, Medicare or Medicaid, and it does not say which denials were correct.
How to use it: Use it to see that denials are common and that a denial is not a judgment about you. Do not use it to predict whether your own claim will be paid or your appeal will win.

HealthCare.gov marketplace insurers denied 37% of out-of-network claims in plan year 2024.

37% of out-of-network claims denied (2024 plan year)

Who it covers: Insurers selling marketplace plans on HealthCare.gov (not state-run marketplaces), as reported to the Centers for Medicare & Medicaid Services. Claims for care already received.
Source: KFF, Claims Denials and Appeals in ACA Marketplace Plans in 2024 (24 March 2026)
What it does not show: KFF reports this separately from the 19% in-network rate, and the two should not be averaged by a reader. It does not say why the claims were denied or how many were paid after the person appealed. It says nothing about employer plans.
How to use it: Use it as a reason to check network status before care and to ask whether the No Surprises Act applies. Do not read it as a rule that out-of-network claims are always denied.

Fewer than 1% of denied in-network marketplace claims were appealed in 2024.

Fewer than 1% appealed (at least 262,982 appeals of about 85 million denied in-network claims) (2024 plan year)

Who it covers: Internal appeals filed with insurers selling marketplace plans on HealthCare.gov, out of in-network claim denials.
Source: KFF, Claims Denials and Appeals in ACA Marketplace Plans in 2024 (24 March 2026)
What it does not show: KFF calls the appeal count a minimum because the federal data hides small values. The figure does not show why people did not appeal, and it does not cover employer plans, Medicare or Medicaid.
How to use it: Use it to see that most people do not appeal. Do not read it as a sign that appeals are pointless; it only counts how many were filed.

KFF reports that marketplace insurers upheld 66% of internal appeals in 2024.

66% of appeals upheld (165,863 upheld), as KFF states it (2024 plan year)

Who it covers: Internal appeals decided by insurers selling marketplace plans on HealthCare.gov.
Source: KFF, Claims Denials and Appeals in ACA Marketplace Plans in 2024 (24 March 2026)
What it does not show: KFF's own two counts (165,863 upheld and at least 262,982 appealed) divide to about 63%, not 66%. KFF notes the appeal count is a minimum because the federal data hides small values, which probably explains the gap. There is no national overturn rate for external review: KFF says the share of external appeals upheld or overturned could not be calculated.
How to use it: Quote it only as KFF's figure for 2024. Do not subtract it from 100 to get an overturn rate, and do not use it to predict your own appeal.

Marketplace enrollees filed at least 5,881 external appeals in 2024, but the share that succeeded cannot be calculated.

At least 5,881 external appeals, about 4% of upheld internal appeals (2024 plan year)

Who it covers: External review requests from people with marketplace plans on HealthCare.gov.
Source: KFF, Claims Denials and Appeals in ACA Marketplace Plans in 2024 (24 March 2026)
What it does not show: KFF says the share of external appeals that were upheld or overturned could not be calculated, because the federal data hides small values. No nationwide official overturn rate for external review was found, for either the federal process or private independent review organizations. State agencies publish their own figures, shown in other rows.
How to use it: Use it to see that very few people reach external review. Do not quote an external review success rate for the whole country; none exists in the sources we use.

KFF lists the reasons marketplace insurers reported for denied in-network claims in 2024, where reported: 36% other, 25% administrative, 9% lack of prior authorization or referral, 5% lack of medical necessity.

"Other" 36%, administrative reasons 25%, lack of prior authorization or referral 9%, lack of medical necessity 5% (2024 plan year)

Who it covers: Reasons reported for denied in-network claims by insurers selling marketplace plans on HealthCare.gov, where reported.
Source: KFF, Claims Denials and Appeals in ACA Marketplace Plans in 2024 (24 March 2026)
What it does not show: KFF reports these percentages "where reported". The four figures add up to 75%, and we do not know how multiple reasons on one claim were counted. The figures cover HealthCare.gov states only and say nothing about employer plans, Medicare or Medicaid.
How to use it: Use it to see which reasons insurers reported most often. Do not read it as the chance that your own denial has any one reason.

Medicare Advantage plans denied 7.7% of prior authorization determinations in full or in part in 2024.

7.7% denied in full or in part (4.1 million of about 52.8 million determinations) (2024)

Who it covers: Medicare Advantage plans (Part C), prior authorization determinations as reported to the Centers for Medicare & Medicaid Services. KFF's analysis of that data.
Source: KFF, Medicare Advantage Insurers Made Nearly 53 Million Prior Authorization Determinations in 2024 (28 January 2026)
What it does not show: This is KFF's analysis of plan-reported data, not a government publication. The rate ranged by insurer from 4.2% (Elevance Health) to 12.8% (UnitedHealthcare). It does not say how many denials were correct, and it does not cover Original Medicare, employer plans or marketplace plans.
How to use it: Use it to see that prior authorization denials in Medicare Advantage are common. Do not use it to guess whether your own request will be denied.

Medicare Advantage enrollees and providers appealed 11.5% of prior authorization denials in 2024.

11.5% of denials appealed (2024)

Who it covers: Medicare Advantage plans (Part C), prior authorization denials, KFF's analysis of data reported to the Centers for Medicare & Medicaid Services.
Source: KFF, Medicare Advantage Insurers Made Nearly 53 Million Prior Authorization Determinations in 2024 (28 January 2026)
What it does not show: The share appealed ranged by insurer from 1.6% (Kaiser Foundation Health Plan) to 19.9% (CVS Health). A separate Office of Inspector General figure of 1% (see the 2014 to 2016 row) covers prior authorization and payment denials together, which is why the two differ.
How to use it: Use it to see that most denied requests are never appealed. Do not combine it with the 1% figure from a different report.

Medicare Advantage plans partly or fully overturned 80.7% of prior authorization appeals in 2024.

80.7% of appeals partially or fully overturned (2024)

Who it covers: Appeals of Medicare Advantage prior authorization denials, KFF's analysis of data reported to the Centers for Medicare & Medicaid Services.
Source: KFF, Medicare Advantage Insurers Made Nearly 53 Million Prior Authorization Determinations in 2024 (28 January 2026)
What it does not show: It covers only the 11.5% of denials that were appealed, and people who appeal may differ from people who do not. By insurer it ranged from 51.0% (Kaiser Foundation Health Plan) to 95.5% (Centene). It does not apply to marketplace plans, employer plans or other kinds of Medicare Advantage decisions.
How to use it: Use it as one reason to appeal a Medicare Advantage prior authorization denial. Do not read it as a promise, and do not apply it to other kinds of coverage.

From 2014 to 2016, Medicare Advantage plans overturned 75% of their own denials on appeal.

75% of denials overturned on appeal (about 216,000 a year) (2014 to 2016)

Who it covers: Medicare Advantage organizations, denials of services and payments that were appealed, from a federal Office of Inspector General review.
Source: Office of Inspector General, Medicare Advantage Appeal Outcomes and Audit Findings Raise Concerns About Service and Payment Denials (report OEI-09-16-00410, 25 September 2018)
What it does not show: The data are from 2014 to 2016, so this is not a current rate. Only a small share of denials was appealed (see the next row). The report also found that in 2015 the Centers for Medicare & Medicaid Services cited 56% of audited contracts for inappropriate denials.
How to use it: Use it as long-standing evidence that many Medicare Advantage denials do not hold up on appeal. Do not use it as a current rate.

From 2014 to 2016, only 1% of Medicare Advantage denials were appealed by enrollees or providers.

1% of denials appealed (2014 to 2016)

Who it covers: Medicare Advantage organizations, denials of services and payments (prior authorization and payment denials together), from a federal Office of Inspector General review.
Source: Office of Inspector General, Medicare Advantage Appeal Outcomes and Audit Findings Raise Concerns About Service and Payment Denials (report OEI-09-16-00410, 25 September 2018)
What it does not show: The 1% covers prior authorization and payment denials together, which is why it is much lower than the 11.5% KFF reports for prior authorization alone in 2024. The two come from different reports and different years and should not be combined or compared as a trend.
How to use it: Use it to see that, historically, very few denials were challenged. Do not read it as a current appeal rate.

In a one-week sample from June 2019, 13% of denied Medicare Advantage prior authorization requests met Medicare coverage rules.

13% of denied prior authorization requests met Medicare coverage rules (1 to 7 June 2019 (sample))

Who it covers: A sample of denials at 15 of the largest Medicare Advantage organizations, from a federal Office of Inspector General review.
Source: Office of Inspector General, Some Medicare Advantage Organization Denials of Prior Authorization Requests Raise Concerns About Beneficiary Access to Medically Necessary Care (report OEI-09-18-00260, 27 April 2022)
What it does not show: It is a one-week sample from 2019, not a count of all denials, and Medicare Advantage coverage rules changed from 2024. The same report found that 18% of denied payment requests met Medicare coverage and plan billing rules.
How to use it: Use it as evidence that some denials are errors under Medicare's own rules. Do not use it to estimate the chance that your denial is one of them.

In 2019, Medicaid managed care plans denied about 1 in 8 prior authorization requests.

About 2.2 million requests denied, 1 in 8 (12.5%) (2019)

Who it covers: 115 Medicaid managed care plans run by the 7 largest parent companies in 37 states, from a federal Office of Inspector General review.
Source: Office of Inspector General, High Rates of Prior Authorization Denials by Some Plans and Limited State Oversight Raise Concerns About Access to Care in Medicaid Managed Care (report OEI-09-19-00350, 17 July 2023)
What it does not show: It covers only those plans and that year. Twelve plans had denial rates above 25%. The report puts Medicare Advantage at 5.7% that year. It does not say how many denials were correct.
How to use it: Use it to see that denial rates vary widely between plans. Do not use it as the denial rate for your state or your plan.

In 2019, Medicaid managed care plans reversed 36% of the denials that were appealed.

36% of appealed denials reversed by the plan (2019)

Who it covers: 115 Medicaid managed care plans run by the 7 largest parent companies in 37 states, from a federal Office of Inspector General review.
Source: Office of Inspector General, High Rates of Prior Authorization Denials by Some Plans and Limited State Oversight Raise Concerns About Access to Care in Medicaid Managed Care (report OEI-09-19-00350, 17 July 2023)
What it does not show: Enrollees appealed 11% of denials, and only 2% of upheld denials went on to a state fair hearing. Only 14 of the 37 states offered external medical review. The report compares this 36% with 82% for Medicare Advantage, but the two programs differ.
How to use it: Use it to see that plan appeals do change some Medicaid managed care decisions. Do not assume the same result for your plan.

California's Department of Managed Health Care says about 78% of people who request an Independent Medical Review receive the service.

Approximately 78% (Cited from the Department's 2025 Annual Report)

Who it covers: People who requested an Independent Medical Review (California's external review) from health plans regulated by the California Department of Managed Health Care.
Source: California Department of Managed Health Care, frequently asked questions
What it does not show: This is the agency's own figure, not an independent count. The Department's paper form still says approximately 73 percent. It covers only plans the Department regulates, in one state, and it is not a federal or national figure.
How to use it: Use it to see what one state regulator reports about independent review. Do not apply it to another state or to a self-funded employer plan.

In 2025 the California Department of Managed Health Care's dashboard shows reviewers overturned 57.39% of medical necessity Independent Medical Reviews.

57.39% overturned by the reviewer (3,290 medical necessity reviews) (2025)

Who it covers: Medical necessity Independent Medical Reviews of health plans regulated by the California Department of Managed Health Care.
Source: California Department of Managed Health Care, Complaints and Independent Medical Reviews dashboard
What it does not show: The same dashboard shows 23.01% reversed by the plan itself after the request was filed and 19.60% upheld. The Department's separate FAQ figure of approximately 78% is a different measure and should not be added to or compared with these. All of it is the agency's own figure for one state.
How to use it: Use it to see that filing for independent review can change a plan's decision, even before a reviewer rules. Do not treat it as a national rate.

By our arithmetic, about 48% of New York external appeal decisions in the state's public archive were decided wholly or partly for the patient or provider.

About 48% (derived by us: (26,700 overturned + 1,087 overturned in part) divided by (26,700 + 1,087 + 29,677 upheld) = 27,787 of 57,464) (Decisions issued on and after 31 May 2019; counts as displayed on 11 November 2026)

Who it covers: External appeal decisions in the New York Department of Financial Services searchable archive, all coverage types in the archive, including Medicaid, which is the largest group.
Source: New York Department of Financial Services, External Appeals Searchable Archive
What it does not show: The Department publishes the three counts, not this percentage; the 48% is our own calculation, and it will change as the archive grows. The archive covers many kinds of appeals and coverage, so it says little about any one denial.
How to use it: Use it as an example of what one state's public data show. Do not use it for another state, and do not treat it as the chance that your appeal will win.

In 2024, Illinois external reviewers fully overturned 627 of 1,351 eligible denials.

627 of 1,351 eligible reviews fully overturned (about 46 percent); 12 partly overturned; 712 upheld (2024)

Who it covers: External review requests to the Illinois Department of Insurance that were found eligible. Of 4,468 requests received, 3,117 were not eligible.
Source: Illinois Department of Insurance, Office of Consumer Health Insurance 2024 Annual Report
What it does not show: The 46 percent counts only fully overturned decisions and leaves out the 12 partly overturned. Most requests (3,117 of 4,468) were ineligible, often because internal appeals were not finished first. The figure is for one state.
How to use it: Use it to see what one state's regulator reports, and to learn that finishing the internal appeal first matters. Do not apply it to another state.

69% of insured adults with a denied claim did not know whether they had a right to appeal.

69% did not know whether they had appeal rights (2023)

Who it covers: Insured adults in the United States who reported a denied claim in the past 12 months, from the 2023 KFF Survey of Consumer Experiences with Health Insurance (3,605 insured adults, surveyed 21 February to 14 March 2023).
Source: KFF, Consumer Survey Highlights Problems with Denied Health Insurance Claims (2023 KFF Survey of Consumer Experiences with Health Insurance)
What it does not show: This is what people said in a survey, not a count of claims or appeals. Not knowing whether you have appeal rights is not the same as having none. The survey does not show what rights these respondents had.
How to use it: Use it to see why this site starts with whether you can appeal. Do not read it as a share of people who are not allowed to appeal.

86% of insured adults with a denied claim did not know which government agency to call.

86% did not know which government agency to call (2023)

Who it covers: Insured adults in the United States who reported a denied claim in the past 12 months, from the 2023 KFF Survey of Consumer Experiences with Health Insurance (3,605 insured adults, surveyed 21 February to 14 March 2023).
Source: KFF, Consumer Survey Highlights Problems with Denied Health Insurance Claims (2023 KFF Survey of Consumer Experiences with Health Insurance)
What it does not show: This is what people said in a survey, not a count of claims or appeals. The right agency depends on your plan type (for example the federal Employee Benefits Security Administration for many employer plans or your state insurance department for insured plans).
How to use it: Use it to see why we say who regulates each kind of plan. Do not treat it as a count of people who got no help.

15% of insured adults with a denied claim filed a formal appeal.

15% filed a formal appeal (2023)

Who it covers: Insured adults in the United States who reported a denied claim in the past 12 months, from the 2023 KFF Survey of Consumer Experiences with Health Insurance (3,605 insured adults, surveyed 21 February to 14 March 2023).
Source: KFF, Consumer Survey Highlights Problems with Denied Health Insurance Claims (2023 KFF Survey of Consumer Experiences with Health Insurance)
What it does not show: This is what people said in a survey, not a count of claims or appeals. Survey answers come from people's memory, so this differs from the claim counts that insurers report (such as the under 1% of denied marketplace claims that were appealed). The different sources and populations should not be combined.
How to use it: Use it to see that formal appeals are uncommon. Do not read it as the chance that an appeal succeeds.

At the Medicare Administrative Law Judge level, 21.3% of decisions were fully favorable in fiscal year 2025.

21.3% fully favorable (fiscal year 2025: 1.5% partially favorable, 61.1% unfavorable, 16.2% dismissed) (Fiscal year 2025)

Who it covers: Appeals decided by Administrative Law Judges at the Office of Medicare Hearings and Appeals, all appellants (mostly providers).
Source: Office of Medicare Hearings and Appeals, decision statistics
What it does not show: The figures are not broken out for appeals filed by people on Medicare. Most appellants are providers. This is a third-level appeal, so these cases already went through two earlier levels. The page was read through a third-party service, so check it against the live page before relying on it.
How to use it: Use it to understand that later levels of Medicare appeal are harder than earlier ones. Do not read it as the chance that your case will win at that level.

Sources last checked 12 November 2026. Found a mistake? Report it.