How often are claims denied?
Across 2023 ACA marketplace plans, insurers denied about 19% of in-network claims, with plan-level denial rates ranging from 1% to 54%.
Source: KFF — Claims Denials and Appeals in ACA Marketplace Plans
Medicare Advantage plans denied about 6% of prior authorization requests in 2021 — and 11% of those denials met Medicare coverage rules, meaning they were wrongly denied.
Source: HHS OIG — Some Medicare Advantage Denials Raise Concerns About Beneficiary Access
Industry estimates place the annual value of denied US medical claims at approximately $262 billion, with about 86% of denials considered "potentially avoidable."
Source: Change Healthcare / Optum Revenue Cycle Denials Index (widely cited by AHIMA and HFMA). Figures fluctuate year to year.
How often do patients appeal?
Fewer than 1% of in-network claim denials in ACA marketplace plans are appealed by the consumer. Non-appeals account for the vast majority of denied care.
Source: KFF — Claims Denials and Appeals in ACA Marketplace Plans
Under the Affordable Care Act, you have the right to an internal appeal with your insurer and, if that fails, an independent external review by a third party. ERISA plans have parallel protections.
Source: CMS — Internal Claims, Appeals & External Review Processes
How often do appeals succeed?
When consumers did appeal denied in-network ACA claims in 2023, insurers overturned about 44% of those denials in the consumer's favor through internal review alone.
Source: KFF — Claims Denials and Appeals in ACA Marketplace Plans
Of the Medicare Advantage prior-authorization denials that were appealed between 2014 and 2016, approximately 82% were fully or partially overturned — suggesting a very high baseline of wrongful denials that patients simply don't know to challenge.
Source: HHS OIG — Medicare Advantage Appeal Outcomes (OEI-09-16-00410)
Independent external-review agencies overturn roughly 40-50% of denials they evaluate — a meaningful second chance once the insurer's internal process is exhausted. Rates vary by state and denial type.
Source: Aggregate state Departments of Insurance external-review reports & KFF review data
Key deadlines every patient should know
- 180 days — the typical maximum window to file an internal appeal under ACA-compliant plans (counted from the date on the denial letter). Some plans allow longer.
- 4 months — standard window for requesting external review after internal appeal denial.
- 72 hours — maximum decision time for expedited/urgent appeals involving immediate health risk.
- 30 days — typical decision window for pre-service (pre-treatment) appeals.
- 60 days — typical decision window for post-service (after-care) appeals.
Source: CMS — Internal Claims, Appeals & External Review Regulations. Always check your specific plan documents and state law — deadlines can differ, especially for non-ACA plans.
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