Medicare Advantage Prior Authorization: What the Data Really Shows

If you are enrolled in a Medicare Advantage plan — or comparing plans before the Annual Enrollment Period closes on December 7 — there is one feature of your coverage that deserves far more scrutiny than it typically gets: prior authorization. This is the process by which your plan requires your doctor to obtain advance approval before you can receive certain treatments, procedures, diagnostic tests, or medications. Federal data now publicly available from the Centers for Medicare and Medicaid Services reveals just how dramatically this practice varies from plan to plan, and the picture it paints raises serious questions about whether beneficiaries are receiving medically necessary care without unnecessary delays or denials.

Prior authorization has been part of managed care for decades, but its use in Medicare Advantage has expanded significantly as enrollment in these private plans has surged. According to CMS.gov data, more than 33 million Medicare beneficiaries — roughly 54 percent of all people with Medicare — were enrolled in Medicare Advantage plans in 2024, up from about 42 percent just five years earlier. Unlike Original Medicare, which generally pays for any covered service that you and your doctor determine is medically necessary, Medicare Advantage plans are administered by private insurers who are permitted to require prior authorization for a wide range of services. That means your plan may need to sign off before you can receive an MRI, a skilled nursing facility stay, home health services, outpatient surgery, or certain specialty drugs. The critical question the new federal data is beginning to answer — though not yet completely — is how often plans are saying no, and whether those denials hold up when challenged.

According to CMS.gov data from the Medicare Advantage Prior Authorization and Step Therapy for Part B Drugs dataset, the variation in denial rates across plans is striking. Some plans deny prior authorization requests at rates below 2 percent, while others deny them at rates exceeding 10 percent for certain service categories. These are not marginal differences. A plan that denies one in ten prior authorization requests is creating a meaningfully different experience for its members than one that denies fewer than one in fifty. The same dataset shows that the vast majority of prior authorization denials that are formally appealed are ultimately overturned in the beneficiary's favor — a pattern that advocates argue suggests many initial denials lack adequate clinical justification.

Data Snapshot: According to CMS.gov data published in the 2024 Medicare Advantage and Part D Contract and Enrollment Data, there were 861 Medicare Advantage organizations offering 4,296 plan options nationwide in 2024. CMS star ratings data for that same year showed that fewer than 10 percent of Medicare Advantage contracts earned 5 stars, while roughly 30 percent earned 3.5 stars or below — ratings that factor in member experience metrics including how well plans handle care coordination and appeals. When shopping on Medicare.gov's Plan Finder, star ratings are one of the few consumer-facing signals currently available about plan quality, since prior authorization denial rates are not yet integrated into that tool in a format that is easy to compare.

The Medicare Rights Center, a national nonprofit that provides direct assistance to people with Medicare, has been analyzing this public data and calling for greater transparency. Their core argument is that while the raw data exists on CMS.gov, navigating federal datasets requires a level of technical comfort that most beneficiaries — and frankly most people of any age — do not have. What advocates want is for CMS to incorporate prior authorization metrics directly into the Medicare Plan Finder at Medicare.gov, so that when you are comparing plans during the Annual Enrollment Period, you can see not just monthly premiums and star ratings but also how often a plan denies prior authorization requests and how quickly it processes them. Until that happens, beneficiaries who want this information need to either dig into CMS datasets themselves or work with a trained counselor.

Here is what you can do right now if you are already enrolled in a Medicare Advantage plan. You have the right under federal law to request a complete list of services that require prior authorization directly from your plan. Your plan's Evidence of Coverage document — which should arrive in your mailbox each fall before the Annual Enrollment Period begins — also lists these requirements in detail. Read that document carefully, particularly if you have a chronic condition, are scheduled for surgery, or anticipate needing specialist care, home health services, durable medical equipment, or post-acute rehabilitation in the coming year. If your doctor recommends a service and you are uncertain whether it requires prior authorization, call your plan's member services line before the appointment. Obtaining prior authorization after a service has already been provided is far more difficult than securing it in advance, and retroactive denials can leave you responsible for the full cost.

If your plan denies a prior authorization request, you have a structured set of options. First, your doctor can submit additional clinical documentation to support the medical necessity of the service — many initial denials are reversed at this stage without a formal appeal. Second, you can file a formal appeal. Under CMS rules that took effect in 2024, Medicare Advantage plans must respond to standard prior authorization requests within 7 calendar days and to urgent requests within 72 hours. For services already received, payment appeals must be resolved within 60 days. If the plan upholds its denial after your first appeal, you can escalate to an Independent Review Entity, and then to an Administrative Law Judge if the amount in dispute meets the threshold — currently $180 or more in 2025. The appeals process has real force behind it. Studies have consistently shown that beneficiaries who appeal prior authorization denials prevail in a substantial share of cases, which underscores the importance of not accepting an initial denial as final.

The 2024 CMS prior authorization rule also requires plans to provide specific clinical reasons for any denial — not a vague statement that the service is not covered, but an explanation of exactly what clinical criteria were not met and what information might change the outcome. This is a meaningful improvement over past practice, where generic denial letters left beneficiaries and their physicians guessing about next steps. However, advocacy organizations note that enforcement of these requirements remains inconsistent, and that CMS needs to conduct more rigorous auditing of plan compliance to ensure the rules are being followed in practice, not just on paper.

One protection that is already firmly in place: Medicare Advantage plans cannot require prior authorization for emergency services, and they cannot impose prior authorization requirements that are more restrictive than Original Medicare for services that Original Medicare covers without restriction. In practice, however, the boundary between what requires authorization and what does not can be ambiguous, particularly for services like inpatient hospital stays, post-acute skilled nursing facility care, and home health — precisely the services that older adults are most likely to need after a serious illness or surgery. If you are hospitalized and your plan's utilization review team determines you are ready for discharge before you or your physician agrees, you have the right to request a fast appeal through your Beneficiary and Family Centered Care Quality Improvement Organization, known as a BFCC-QIO. The plan cannot discharge you while that appeal is pending, and the QIO must issue a decision within one business day of receiving your medical records.

For beneficiaries who are weighing a switch back to Original Medicare to avoid prior authorization requirements altogether, the trade-offs deserve careful thought. Original Medicare does not use prior authorization for most covered services, which is a significant advantage in terms of access and simplicity. However, Original Medicare has no annual out-of-pocket maximum, meaning a serious illness could expose you to unlimited cost-sharing without a Medigap supplemental policy. Medigap plans — sold by private insurers and standardized by letter (Plan G and Plan N are the most popular options today) — typically cost between $100 and $300 per month depending on your age, location, and the plan letter you select. Plan G, which covers nearly all Original Medicare cost-sharing except the Part B deductible of $257 in 2025, is the most comprehensive option currently available to new enrollees.

If you want to switch from Medicare Advantage back to Original Medicare, you can do so during the Annual Enrollment Period (October 15 through December 7) or the Medicare Advantage Open Enrollment Period (January 1 through March 31). The critical caveat: in most states, if you have been enrolled in Medicare Advantage for more than 12 months, Medigap insurers can use medical underwriting to deny you coverage or charge higher premiums based on your health history. The states that offer additional protections through birthday rules — giving you a 30-day window each year to switch Medigap plans without underwriting — are California, Idaho, Illinois, Kentucky, Louisiana, Maine, Maryland, Missouri, Nevada, New Jersey, New York, Oklahoma, and Oregon. If you live in one of these states, your annual birthday window may give you more flexibility than you realize.

On the legislative front, the Improving Seniors' Timely Access to Care Act would codify many of the 2024 CMS reforms into statute while adding additional protections, including real-time prior authorization for routinely approved services and stricter transparency requirements. The bill has passed the House with strong bipartisan support in multiple sessions but has not yet cleared the Senate. If prior authorization has affected your care or the care of someone you love, contacting your senators directly is one of the most concrete actions you can take.

When evaluating Medicare Advantage plans — whether during the Annual Enrollment Period or after a qualifying life event that triggers a Special Enrollment Period — prior authorization policies belong on your checklist alongside premiums, deductibles, copays, provider networks, and drug formularies. Ask your plan or a licensed Medicare counselor specifically which services relevant to your health situation are likely to require prior authorization. Your State Health Insurance Assistance Program, known as SHIP, offers free, unbiased counseling and can help you compare plans in your area. Find your local SHIP counselor at shiphelp.org. The Medicare Plan Finder at Medicare.gov allows side-by-side plan comparisons on cost and coverage, and while prior authorization data is not yet integrated there in a consumer-friendly format, a SHIP counselor can help you cross-reference plan information with CMS public datasets and interpret what the numbers mean for your specific situation.

The bottom line is straightforward: prior authorization is one of the most consequential ways that Medicare Advantage differs from Original Medicare, and federal data confirms that how aggressively plans use this tool varies enormously — from plans that rarely deny requests to those that deny more than one in ten. Until CMS makes this data easier to find and compare, the responsibility falls on beneficiaries to ask the right questions before enrolling, know their appeal rights when a denial arrives, and choose plans with a track record of approving medically necessary care. You should not have to navigate this alone — SHIP counselors, the Medicare Rights Center helpline at 800-333-4114, and Medicare.gov are all free resources available to help you.