Advantage Plans Said No 4.1 Million Times in 2024. Four in Five Appeals Won. Nine in 10 Denials Were Never Appealed.

Picture a 72-year-old released after a five-day hospital stay for a bad fall. Her surgeon sends her to a skilled nursing facility (SNF) for rehabilitation. Her Medicare Advantage (MA) plan sends back a denial: not medically necessary.

She generally has 65 days to appeal, or she can request an expedited decision when waiting could jeopardize her health or ability to recover. She does neither. She pays out of pocket, goes home before she is ready or settles for less care than her doctor ordered. That denial is one of millions, but the more revealing number is how often the answer changes when someone challenges it.

Read the Numbers in the Right Order

A KFF analysis counted 52.8 million prior authorization determinations by MA insurers in 2024, about 1.7 requests per enrollee. Plans fully or partially denied 4.1 million of them, or 7.7%. Only 11.5% of those denials were appealed. When beneficiaries or their providers did appeal, insurers overturned 80.7%.

That does not prove four out of five original decisions were careless. Some appeals succeed because the physician adds records, clarifies why the care is necessary or supplies information missing from the first request. But that distinction offers little comfort to the patient waiting for rehabilitation. Whether the problem was the decision or the documentation, the appeal moved the claim from no to yes. The striking gap is between the number of reversals and the number of people who ever asked for another look. Nearly nine in 10 denials stopped at the first answer.

Original Medicare Uses a Much Smaller Gate

Traditional Medicare processed roughly 625,000 prior authorization reviews in the same year and denied about 22.9%. That percentage was higher than the MA denial rate, but it describes a far narrower program. Original Medicare requires prior authorization for only a limited group of services, while MA plans apply it much more broadly. The percentages therefore are not an apples-to-apples comparison. For most care under Original Medicare, the patient and physician never encounter prior authorization at all.

The financial tradeoff still matters. The $202.90 standard Part B premium applies whether someone has Original Medicare or MA. Under Original Medicare in 2026, the beneficiary also faces a $283 Part B deductible, generally 20% coinsurance, a $1,736 Part A hospital deductible per benefit period and $217 a day for SNF care from days 21 through 100.

A Medigap Plan G adds another monthly premium but covers most of that cost sharing after the Part B deductible. An MA plan may carry a lower additional premium and an annual limit on covered in-network spending, but it also brings networks and prior authorization into more treatment decisions. The choice is not simply high premium versus low premium. It is also predictable cost sharing versus more plan control over when care qualifies.

Leaving the Plan May Require Another Approval

An MA member can return to Original Medicare during an eligible enrollment period. Buying Medigap to sit beside it may be harder. Outside the one-time six-month Medigap open enrollment period or another guaranteed-issue protection, insurers in most states can use medical underwriting. A recent hospitalization or newly documented condition may affect whether another carrier approves the application and what it charges. State protections vary, so the move should be handled in the right order. Someone planning to leave MA for Original Medicare plus Medigap should confirm their state rights and obtain written Medigap approval before ending the current plan.

Treat the Denial as the First Answer

The high reversal rate makes three moves worth preparing before a denial arrives:

1. Appeal a disputed denial promptly. The standard filing window is generally 65 days. If waiting could seriously jeopardize health or recovery, request an expedited appeal, which usually requires a decision within 72 hours.
2. Put the physician’s reasoning into the file. Ask the ordering doctor to provide clinical notes explaining why the service is medically necessary and why a lower level of care will not work.
3. Compare plans before enrollment. Review the plan’s prior authorization requirements and its publicly reported authorization metrics, then compare them with an actual Medigap quote and your state’s underwriting rules.

A denial notice is the plan’s first answer, not necessarily its last. The strongest appeal puts the doctor’s reasoning back into the file while there is still time for the care to matter.

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