Medicare Advantage Denial Rates Compared to Traditional Medicare

Medicare Advantage plans deny claims at roughly double the rate of traditional Medicare, and the gap holds steady across specialties, service types, and payers.

Why Medicare Advantage Denial Rates Are Structurally Higher

Health Affairs research puts the average initial MA denial rate at roughly twice that of traditional Medicare. Traditional Medicare rarely requires prior authorization for most services, while MA plans issued nearly 53 million prior authorization determinations in 2024, KFF found. That volume has no equivalent on the fee-for-service side of the program. A single number, doubled and repeated across specialty after specialty and payer after payer, stops looking like noise and starts looking like design. The remainder of this piece works through the mechanisms that produce that number: the administrative architecture of prior authorization itself, the service lines where the gap concentrates, the differences among MA insurers, and the accelerating role of AI-driven claims review on the payer side. Each of those mechanisms compounds the others, and each has a direct financial consequence for practices that treat MA denials as an unavoidable cost of doing business rather than a problem with identifiable, recoverable failure points.

How prior authorization volume creates a structurally different administrative burden for MA practices

The prior authorization system built into Medicare Advantage creates an entire category of administrative work that traditional Medicare simply does not impose, and that work is the primary channel through which payer policy converts into lost practice revenue. Under traditional Medicare, prior authorization is rarely used for most services. Under MA, KFF reports that virtually every enrollee is in a plan that requires prior authorization for at least some services, most often the high-cost ones. By 2026, 95 percent of MA enrollees were in a plan requiring prior authorization for skilled nursing facility stays alone.

The burden goes beyond volume. MA plans apply proprietary clinical criteria that diverge from Medicare's own National Coverage Determinations and Local Coverage Determinations, so a service that is covered under an NCD or LCD can still be denied if the MA plan's documentation requirements, step therapy protocols, or treatment window definitions differ from the original Medicare standard. A practice can follow federal coverage rules to the letter and still lose the claim, because the plan administering that claim is not bound to those rules in the way traditional Medicare is.

The disruption tied to the 2026 MA market added a further complication. Millions of beneficiaries were forced to switch plans that year because of insurer withdrawals and service area reductions, and prior authorizations obtained under a beneficiary's old plan do not carry over to the new one. That produced a wave of authorization-gap denials for services that had already been approved once, under a different plan, for the same patient and the same medical need. MGMA's 2026 Advocacy Agenda documents the resulting burden directly: practices face heavier administrative loads from prior authorization, downcoding, and narrow networks, and MA dynamics reduce yield even when fee schedule rates rise, through denials, documentation disputes, and delays that push up the cost of collecting what is owed. Traditional Medicare gives a practice one set of coverage rules to track. Medicare Advantage gives it dozens, each capable of changing without notice when a beneficiary switches plans.

Where the Denial Gap Is Widest

The gap between MA and traditional Medicare denial rates is not spread evenly across the services Medicare covers. It concentrates in the high-cost, high-acuity categories that make up the largest share of a practice's revenue exposure.

Post-acute care sits at the extreme end of that concentration. KFF reports that MA insurers deny more than half of all prior authorization requests for the most expensive types of post-acute care, including a majority of requests for stays in long-term care hospitals and a majority of requests for inpatient rehabilitation facilities. Those rates run well above the MA program's overall denial rate for services generally. Skilled nursing facility denials follow the same pattern in a different form: the initial denial rate is notable on its own, but the overturn rate on appeal reaches 95 percent, a figure KFF says raises real questions about whether SNF care is being denied on a routine, and routinely inappropriate, basis.

Specialty-level data from Revenue Synergy's report shows the same concentration playing out across outpatient care. Behavioral health carries the highest denial rate in the dataset, with industry-wide figures for the specialty running substantially higher still. Neurology shows elevated initial denial rates, primarily driven by professional-technical split errors on EMG and EEG procedures. Physical therapy carries elevated denial rates and prolonged accounts receivable, centered on 8-minute rule calculation errors, missing KX modifiers when treatment exceeds the 2026 Medicare threshold, and unsigned plans of care. Orthopedics ranks among the highest-denial specialties industry-wide, and primary care is the lowest-denial specialty in the Revenue Synergy dataset.

Advanced imaging carries its own denial profile. Staffingly reports high MA denial rates across MRI, CT, and PET scans, with the sharpest rates concentrated in lumbar MRI, cardiac CT, and oncology PET imaging. Durable medical equipment ranks among the highest-denial categories on MA plans overall, particularly for power mobility devices, CPAP machines, and home oxygen, driven by dense documentation requirements and strict face-to-face encounter rules. Across all of these specialties, authorization-related denial codes account for a large share of total MA denial volume in the Revenue Synergy dataset, with CARC 197 standing as the single largest denial driver across every specialty examined. That single code, tied directly to missing or invalid prior authorization, threads through neurology, physical therapy, orthopedics, imaging, and DME alike. The specific failure points differ by specialty, but the underlying cause repeats: authorization requirements that traditional Medicare does not impose, enforced with a rigidity traditional Medicare does not apply.

Payer-Specific Behavior and Denial Rates Within Medicare Advantage

The denial burden a given practice experiences depends heavily on which MA plans dominate its patient panel, and the spread between the highest-denying and lowest-denying MA insurers is wider than the spread between MA overall and traditional Medicare. Two practices with identical patient populations, identical documentation practices, and identical coding accuracy can carry very different denial burdens purely because one serves a panel weighted toward a higher-denying carrier and the other does not.

The first public disclosures under CMS-0057-F, analyzed by DistilINFO using KFF data, show just how wide that spread runs among major MA insurers in 2025. UnitedHealth Group posted a standard prior authorization denial rate of 17 percent. Kaiser Permanente posted a moderately high denial rate. Appeal outcomes vary just as sharply as initial denial rates do. Centene overturns a very large share of its appealed denials, while Kaiser Permanente overturns a much smaller share, a gap that itself raises questions about how sound the initial denial decisions are at the high end of that range.

A report, OEI-09-24-00331, titled "Medicare Advantage Organizations Overturned Nearly All Appealed Prior Authorization Denials for Skilled Nursing Facility Admission, Raising Concerns About Initial Denials," found that MA organizations overturned nearly all appealed prior authorization denials for SNF admission. The report found that MA organizations overturned nearly all appealed prior authorization denials for SNF admission, making it the most authoritative recent government finding that initial MA denials fail to meet the clinical standard on a systematic basis, not just an occasional one. A congressional investigation added a further data point tying that failure to a specific cause: the three largest MA insurers, UnitedHealthcare, CVS/Aetna, and Humana, increased their denial rates significantly after expanding AI-based authorization review.

Public pressure has not closed that gap. Insurers made voluntary pledges in 2025 to streamline prior authorization, yet by mid-2026, some had already said they would not implement all the initiatives they had promised, and patients, their advocates, and clinicians reported that little had actually improved. Payer behavior inside Medicare Advantage has not corrected itself under public scrutiny, and a practice cannot budget around the assumption that it eventually will. Knowing which insurer applies which criteria to which service, and tracking that knowledge at the payer level rather than the program level, is the operational discipline most practices still lack. Given how wide the spread runs between carriers, that gap in institutional knowledge is a significant inefficiency. A practice with that knowledge can predict and manage its denial rate, while a practice without it faces recurring surprises tied to whichever plan happens to dominate its panel that year.

Why AI-powered payer review is widening the denial gap faster than practices can adapt

MA plans have deployed AI-driven authorization review at a scale and speed that fundamentally changes the economics of denial management, and most practices are responding with tools that address the wrong end of the problem. These review systems process authorization requests in seconds, often without meaningful clinical judgment applied to the decision. A congressional investigation found that the algorithms evaluate requests against clinical criteria almost instantly but cannot tell a request that genuinely fails coverage criteria apart from one where the documentation simply does not match the algorithm's expected format or keyword pattern.

The consequence is a volume of denials issued against clinically appropriate care, later overturned on appeal once a human reviewer actually reads the clinical documentation. The appeal process takes weeks to resolve, and during that time the patient goes without the service while the practice goes without payment. Industry-reported initial claim denial rates have climbed to 11.8 percent even as roughly two-thirds of provider organizations report using some form of AI in their own revenue cycle operations. AI adoption on the provider side and denial rates on the payer side are rising together, not offsetting each other.

Part of the reason is where that provider-side AI investment actually goes. Only a small fraction of it is directed at denial management itself. The overwhelming majority funds ambient clinical documentation and coding assistance, tools that generate paperwork faster without doing anything to prevent that paperwork from being rejected once it reaches a payer's review system. Faster documentation does not help against a payer algorithm trained to flag formatting mismatches rather than genuine coverage failures. What closes that gap is pattern recognition paired with billing specialists who understand how each payer's review system actually behaves in practice, since a payer-blind AI tool applied to a payer-specific problem will surface the wrong exceptions and miss the patterns that only become visible across hundreds of claims processed against the same insurer's criteria. The payer side has scaled its review process through automation built specifically to enforce its own denial logic. Matching that requires more than automation on the provider side. It requires automation combined with institutional knowledge of how each payer's system behaves, which claims it flags, and why.

The revenue consequence of treating MA denials as a fixed cost rather than a recoverable problem

Most of the revenue practices lose to MA denials is recoverable if denials are worked immediately, appealed systematically, and tracked for root-cause patterns before the filing window closes. The scale of what is left on the table when that discipline is missing is significant. Health Affairs research found that MA denials produce a 7 percent net reduction in provider revenue, driven substantially by the fact that a significant portion of denied claims are never appealed at all.

The appeal economics make that gap especially costly. DistilINFO's analysis of KFF data found that a significant share of appealed MA prior authorization denials get overturned, while Staffingly found that very few denied requests are ever appealed in the first place. That combination, a high overturn rate paired with a low appeal rate, means the money being left unclaimed is money the payer has already effectively conceded is owed. For a multi-provider physician group collecting several million dollars annually, an elevated MA denial rate translates into a large volume of claims that never reach payment on first submission, a volume documented by both Health Affairs and Medical Billers and Coders.

The structural forces driving that outcome, prior authorization volume with no equivalent in traditional Medicare, concentrated exposure in post-acute care and specific specialties, wide variation among MA insurers, and AI-driven review scaling faster than manual appeal processes can match, are documented and identifiable rather than random. Practices that track denials at the payer level, appeal on a set schedule tied to filing deadlines, and diagnose root causes by CARC code and specialty are working against a known set of mechanisms rather than an unpredictable cost of doing business. The insurers with the highest overturn rates on appeal, and the OIG's own finding on skilled nursing facility denials, both point to the same conclusion: a large share of what MA plans deny on first pass does not hold up once someone actually appeals it. The revenue sitting behind that fact is simply unclaimed, not lost.