A federal watchdog has put a number on something Medicare Advantage enrollees in rehab facilities have long suspected: a meaningful share of the care insurers initially refuse to pay for turns out, on appeal, to have been medically necessary all along. The finding comes from the three largest Medicare Advantage insurers in the country, measured against 16 smaller competitors, and the gap between what gets denied first and what gets approved on appeal is large enough to raise real questions about how those first denials get made.
What the Federal Watchdog Actually Found
The number comes from data insurers already report to federal regulators every year, and it lands on people at one of the most vulnerable moments in their care — the point where a hospital discharge planner tells them a rehab bed or long-term acute care hospital stay is not covered.
The HHS Office of Inspector General’s report, issued June 8, 2026, examined prior authorization data from June 2024 across the 19 largest Medicare Advantage organizations. Among that group, the three largest MAOs by enrollment denied requests for long-term acute care hospital and inpatient rehabilitation facility admission at higher rates than most of their peers. When enrollees pushed back and appealed those denials, the insurers collectively reversed themselves 36 percent of the time on long-term acute care requests and 43 percent of the time on inpatient rehabilitation requests — meaning more than a third to nearly half of the people who appealed had originally been denied care the plan later agreed they needed.
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The Range Between Insurers Was Enormous
The 36-to-43-percent figures are an average across the three largest insurers, and the individual spread behind that average is wider than the headline number suggests. Overturn rates for inpatient rehabilitation denials ranged, MAO by MAO, from as low as 14 percent to as high as 86 percent. OIG also flagged a specific mechanism behind some of the highest denial rates: contractors hired by the insurers to review these requests were denying a disproportionate share of them, only for the insurer itself to overturn many of those same denials once an enrollee appealed — raising, in the report’s own words, questions about whether those contractors are getting adequate training and oversight.
Trade Reporting Fills In the Names OIG Left Out
OIG’s own report deliberately withholds which three insurers are behind the numbers, describing them only by their rank in enrollment. Trade publication Fierce Healthcare matched that enrollment-based description to the three largest Medicare Advantage insurers — UnitedHealthcare, Humana, and Aetna — and published the individual denial rates behind the average: Aetna denied 80 percent of long-term acute care requests, Humana denied 72 percent, and UnitedHealthcare denied 71 percent, against a 42 percent average among the other 16 insurers OIG reviewed. For inpatient rehabilitation, UnitedHealthcare denied 66 percent of requests, Humana denied 54 percent, and Aetna denied 51 percent, compared with a 41 percent average across the rest of the field.
The insurance industry disputes that the denial numbers alone tell the full story. An AHIP spokesperson said in a statement that the findings fail to account for what he called serious, well-documented concerns about wide variations in the cost and quality of post-acute care and skilled nursing facilities. A companion OIG report released the same day found an even starker pattern for skilled nursing facility admissions: MAOs denied 12 percent of those requests on average, but overturned 95 percent of the denials that enrollees actually appealed.
This Warning Has Been Building Since 2022
This is not the first time OIG has raised this exact alarm. A 2022 OIG report on Medicare Advantage prior authorization broadly found that some denials raised concerns about beneficiary access to medically necessary care, and this year’s report was built specifically to dig deeper into the post-acute care corner of that problem — long-term acute care and inpatient rehab, the settings people rely on to recover after a hospital stay for a stroke, a major surgery, or a serious injury. Four years of watchdog findings pointing at the same underlying pattern suggests this is a structural feature of how these plans manage post-acute care requests, not an isolated data blip from a single review period.
What CMS Has (and Hasn’t) Done About It
OIG’s report comes with two recommendations to CMS: start regularly collecting request-level prior authorization data that includes service type and which contractor handled each denial, and dig into why overturn rates vary so widely between insurers and their contractors. As of this report, both recommendations are listed as open and unimplemented, with an update expected by December 7, 2026, and CMS did not explicitly agree or disagree with either one when the report was finalized. In practice, that means the oversight gap the report identifies is not yet closed, and enrollees currently navigating a denial are working within the same system the audit describes.
What This Means If You’re the One Being Denied
The practical lesson in these numbers is not that appeals always work, but that a first denial is not the final word nearly as often as it might feel in the moment. Medicare’s own guidance on Medicare Advantage appeals lays out the process: the plan’s denial notice must explain how to appeal, the enrollee (or a doctor acting on their behalf) generally has time to file, and the plan is required to decide within a set number of days — faster, on an expedited basis, if waiting would jeopardize the person’s health or ability to recover. Given how often these specific rehab and long-term acute care denials get reversed once someone appeals, the OIG data is itself a case for treating a denial letter as the start of the process rather than the end of it, particularly for anyone facing a discharge into a lower level of care than a doctor originally recommended.
This article was produced with AI assistance and reviewed by a human editor. Figures are linked to their primary sources; where a claim could not be verified from the public record, we say so.
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