Medicare Advantage Post-Acute Denials Are Feeding Hospital Revenue Leakage

Denial rates are falling, but leakage is not. How many MA post-acute denials is your team appealing?

By Cheryl Ericson, RN, MS, CCDS, CDIP

Initial denial rates are finally falling. Revenue leakage is not. Kodiak’s March 2026 report found hospitals on its platform lost $48.4 billion in net revenue in 2025 to final denials and bad debt, up more than 25% from $38.6 billion. Clinical denials for prior authorization and medical necessity accounted for virtually all of the increase in denial rates. Medicare Advantage (MA) is where that pressure concentrates. Hospital frustration is leading to a growing number of health systems to drop MA plans due to payment and authorization practices.

MA Denial Rates Run Far Above Traditional Medicare

In Kodiak’s September report, Unyielding Denials, MA inpatient initial denials improved to 9.15% in the first half of 2026 from 10.75%, but remain more than double the 4.21% for traditional Medicare. Prior authorization and precertification denials drive much of the gap: 2.48% for MA versus 0.02%. MA inpatient final denials are 4.54% of net patient service revenue, more than three times the 1.24% for traditional Medicare. As margins remain tight, MA plan denial rates remain significant with payer mix shifting towards a higher percentage of MA beneficiaries due to rising volumes of uninsured patients at many hospitals.   

Post-Acute Denials Are Often Overlooked

KFF reports that HHS Office of Inspector General found MA insurers denied 65% of requests for long-term care hospital stays, 54% for inpatient rehabilitation, and 12% for skilled nursing. Encouragingly the data also shows appeals work with plans approving 95% of appealed skilled nursing denials. Yet only 18% of skilled nursing denials were appealed, along with 31% for rehabilitation and 36% for long-term care hospitals.

From Post-Acute Denial to Revenue Leakage

Kodiak’s data does not isolate post-acute denials, but the mechanism is clear. A denied or delayed authorization leaves a discharge-ready patient in an acute bed. MedPAC’s preliminary findings show median acute stays before transfer of nine days for MA enrollees versus six for fee-for-service before inpatient rehabilitation, and 21 versus 13 before a long-term care hospital. The American Hospital Association attributes the pattern to prior authorization delays. Under case-based inpatient payment, those extra days typically add cost without adding payment. In fact, Becker’s recently cited post-acute discharge delays among the top hospital challenges in 2025.

Now add the clinical denials Kodiak tracks. Clinical initial denials rose to 2.6% in 2025 from 2.4%, and they are hard to overturn with the rate slipping to 42.1% from 42.7%. Denials that are never appealed or never overturned become final denials, and the median final denial rate rose to 2.7% from 2.5%.

Where Physician Advisors Make the Difference

MA plans must follow Traditional Medicare coverage criteria, including inpatient admission rules at 42 CFR 412.3 (see 42 CFR 422.101(b)(2)). Enforcing that takes physician-level work:

• Post-acute authorization: early physician escalation and peer-to-peer review to shorten avoidable days.
• Clinical denials: arguments tied to the regulation, not generic templates.
• Appeal discipline: appeal by default, with opt-outs documented.
• Payer-level tracking: initial and final denial rates reported separately for MA and traditional Medicare.

The Real Question to Ask

The question is no longer only whether your initial denial rate is falling. It is how many denials, including post-acute authorizations, go unchallenged before they become final write-offs.