KFF: Medicare Advantage insurers denied 4.1 million prior authorization requests in 2024, and 80.7 percent of appeals succeeded

Medicare Advantage insurers made nearly 53 million prior authorization determinations in 2024 and fully or partly denied 4.1 million of them, according to a KFF analysis of federal data published January 28, 2026 ^[1]. Only 11.5 percent of those denials were appealed — but 80.7 percent of the appeals that were filed overturned the original decision, either partly or fully ^[1].

What the data show

Total determinations rose to 52.8 million in 2024 from 49.8 million in 2023 and 37.1 million in 2019 ^[1]. KFF attributes most of the growth to enrollment: Medicare Advantage grew from 22 million people in 2019 to 33 million in 2024 ^[1]. On a per-person basis, requests were flat — 1.7 per enrollee in 2024, down slightly from 1.8 in 2023 and the same as 2019 ^[1].

The denial rate moved up. Insurers denied 7.7 percent of requests in 2024, compared with 6.4 percent in 2023 and 7.4 percent in 2022 ^[1]. Appeals remain rare but more common than they used to be: 11.5 percent of denials were appealed in 2024, versus 11.7 percent in 2023 and 7.5 percent in 2019 ^[1]. In every year KFF examined, more than eight in ten appeals reversed the initial denial ^[1]. KFF notes these were services a clinician had ordered and that were ultimately judged necessary, but that may have been delayed by the appeal step — delays that "may have negative effects on a patient's health" ^[1].

Denial rates varied widely by company. Elevance Health had 3.0 requests per enrollee and denied 4.2 percent; UnitedHealth Group had among the lowest request volumes at 1.0 per enrollee but the highest denial rate at 12.8 percent; Centene had both a high volume (2.9 per enrollee) and a high denial rate (12.3 percent) ^[2].

Traditional Medicare works differently. Only a limited set of services — certain outpatient hospital services, non-emergency ambulance transport and durable medical equipment — require prior authorization there ^[1]. That produced just over 625,000 requests in fiscal year 2024, about 2 per 100 beneficiaries, though a larger share (22.9 percent, under 150,000) was denied ^[1]. By contrast, 99 percent of Medicare Advantage enrollees face prior authorization for at least some services, most often higher-cost care like inpatient stays, skilled nursing stays and chemotherapy ^[1].

Why it matters for patients

The headline number for anyone who has had a coverage request turned down is the 80.7 percent overturn rate paired with the 11.5 percent appeal rate ^[1]. Taken together, the data suggest most denials are never challenged, and most of the ones that are challenged do not hold up.

For GLP-1 medications specifically, this analysis cannot tell you much. CMS collects these figures at the contract level and does not report requests or denials by type of service or type of plan, so there is no way from this data to see how often prior authorization is used for semaglutide (Ozempic, Wegovy, Rybelsus), tirzepatide (Mounjaro, Zepbound) or any other drug ^[1]. KFF argues that service-level data "could help inform consumers in choosing among plans," and that the current reporting cannot show whether some enrollees carry a heavier prior authorization burden than others ^[1]. How much of the 4.1 million denials involved obesity or diabetes drugs is not known from these sources.

KFF polling cited in the analysis found most people see insurer delays and denials as a problem, with about two-thirds of Medicare beneficiaries calling it a major problem ^[1].

What happens next

• In June 2025, major insurers pledged to improve prior authorization, including cutting the volume of services subject to it by January 1, 2026 ^[2].
• On January 1, 2026, the administration launched the Wasteful and Inappropriate Spending Reduction (WISeR) model, testing enhanced technology for prior authorization on a select set of services in traditional Medicare in six states ^[1].
• CMS is running a pilot this year to collect more detailed prior authorization data at the plan and service level, and says it expects to expand the requirement to all plans in 2027 ^[1].
• Bipartisan bills in Congress, the Improving Seniors' Timely Access to Care Act (S. 1816 and H.R. 3514), would codify and expand recent prior authorization rule changes for Medicare Advantage ^[1][2]. Neither source reports a scheduled vote.