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Insurers denied between 12% to 18% of prior authorization requests in 2025: KFF

By Cailey Gleeson Aug 14, 2026 1:00pm
Prior Authorization health insurance Medicare Advantage Medicaid Managed Care

Insurers denied between 12% and 18% of standard prior authorization requests across market segments in 2025, a new analysis from KFF found.

Researchers analyzed Medicare Advantage, Medicaid managed care and Affordable Care Act (ACA) federally facilitated Marketplace (FFM) websites from insurers that had at least 2.5% market share of enrollment in respective segments. Data was collected from 14 unique insurers, representing approximately 71 million enrollees.

On average, 12% of standard prior authorization requests and 10% of expedited requests were denied in Medicare Advantage; 14% of standard requests and 12% of expedited requests were denied in Medicaid managed care; and 18% of standard requests and 16% of expedited requests were denied in ACA FFMs.

Among the six analyzed Medicare Advantage insurers, UnitedHealth Group denied the highest share of standard prior authorization requests (17%) and Centene denied the highest share of expedited requests (13%).

Independence Health Group denied the highest share of standard requests (23%) among Medicaid managed care insurers, while CareSource denied the highest share of expedited requests (21%). 

And, among eight ACA Marketplace insurers, Centene denied the highest share of both standard requests (25%) and expedited requests (23%).

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Although the report notes prior authorization denials are “rarely appealed,” 67% percent of denials were overturned through appeal in Medicare Advantage, 47% in Medicaid managed care and 43% in ACA FFMs.

Data shows that the median time between the submission of a prior authorization request and the determination by the insurer, or response time, for standard requests was about 1 day for Medicare Advantage, Medicaid managed care and the ACA Marketplace. The median response time for expedited requests was about half a day for Medicare Advantage, just under 1 day for Medicaid managed care, and 1 day for the ACA Marketplace.

"Despite the regulatory intent to make insurer prior authorization practices more transparent, difficulty locating and interpreting metrics on insurer websites and gaps in how (e.g., a standardized template that insurers are required to use) and what metrics (e.g., denominators and breakouts by service category) must be reported limit the usability of this information directly by the public," KFF researchers wrote.

Researchers say gaps persist in data and understanding surrounding health insurance—especially for consumers. A March 2025 report found one-quarter of insured adults reported difficulties in understanding terms used by insurers.

Insurers are only required to report percentages for prior authorization requests for each metrics, but researchers note numeric counts would provide more context for whether denial rates reflect a “meaningful volume” of requests. 

CMS has updated its prior authorization reporting requirements and proposed new rules that would expand the data insurers must publicly disclose, standardize reporting methods and improve comparisons across health plans. At the same time, Medicare, Medicaid, federal lawmakers and several states are pushing for greater transparency into prior authorization practices, with some states using the resulting data to eliminate or limit authorization requirements for certain services, KFF noted.
Prior Authorization health insurance Medicare Advantage Medicaid Managed Care Affordable Care Act (ACA) Kaiser Family Foundation UnitedHealth Group Centene Corporation Independence Health Group CareSource Finance Providers Payers