A new KFF analysis of the first year of federally mandated insurer reporting finds average 2025 denial rates of 12% in Medicare Advantage, 14% in Medicaid managed care, and 18% in ACA marketplace plans. Denial rates swing widely by insurer from 5% (Elevance) to 17% (UnitedHealth) in Medicare Advantage and as high as 25% (Centene) in ACA plans. The reporting requirement comes from a 2024 CMS final rule that, for the first time, forced Medicaid MCOs and ACA marketplace insurers to disclose this data publicly.
The most telling numbers are not just the denial rates themselves, but what happens when physicians and their staff challenge them. When denials are appealed, they are overturned 67% of the time in Medicare Advantage, 47% in Medicaid, and 43% in ACA plans. That is not a rounding error. It is evidence that a substantial share of initial denials were wrong from the start, and that the burden of correcting them falls on physicians and staff.
Why This Matters for Advocacy
This data validates what ASGE has told CMS directly. In a March 2026 newsletter, ASGE noted that prior auth functions largely as a documentation audit. Clinically justified procedures get denied not because they lack merit, but because a note lacks a specific detail payer are looking for. High overturn rates on appeal are consistent with that pattern. The clinical case was sound all along. This KFF report equips ASGE with fresh, insurer-specific data to cite in both its legislative advocacy and its ongoing push for CMS to require service-level transparency and disclosure of AI and predictive technology use in utilization management.