Prior Authorization in Medicare Advantage: What to Know

October 23, 2026

Patient and physician discuss prior authorization

Prior authorization means your Medicare Advantage plan must approve a service before it will pay for it. If your doctor orders a covered service and the plan has not signed off first, the plan can refuse the claim. Original Medicare uses this rule far less often. If you are choosing a plan, or already in one and frustrated by delays, this guide explains what gets reviewed, how fast the plan has to answer, and what to do after a denial.

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TL;DR

Almost every Medicare Advantage enrollee needs approval for some services. KFF reports that 99% are in plans that require it, most often for costly care such as inpatient stays, skilled nursing and chemotherapy.
As of 2026, plans must answer standard requests within seven calendar days and expedited requests within 72 hours, according to CMS.
Denials are worth appealing. You have 65 days to file, and reported overturn rates are high.
If your plan’s rules do not suit you, you have options. Oregon’s Birthday Rule lets some Medigap holders switch policies without health questions.

What prior authorization is, in plain terms
How common are denials?
The 2026 timelines your plan must follow
What to do when a request is denied
Does Original Medicare have prior authorization too?
Is Medicare Advantage still right for you?
Our perspective: why we talk about this before you enroll
Medigap and the Oregon Birthday Rule: a different route
Work with a local agent who explains before enrolling
Practical habits that prevent approval headaches
FAQ
Sources

What prior authorization is, in plain terms

Prior authorization is a cost-control tool. Researchers describe it as a form of utilization management: a clinician must get the insurer’s approval before providing a service. The plan checks whether the service meets its coverage criteria. If it does, the plan approves it. If not, it denies it.

Two details trip people up.

Your doctor usually does the paperwork. The physician’s office submits the request and the clinical evidence. You are rarely the one filling out forms, but you are the one who waits.

You often find out too late. The same research notes that requirements are often not clearly disclosed or understood until a service is actually rejected at the point of care. A treatment your doctor calls medically necessary can still be denied because it fails the insurer’s own internal criteria.

What typically needs approval

Rules differ from plan to plan, so your plan’s Evidence of Coverage is the final word. Common categories include:

Inpatient hospital stays that are not emergencies
Skilled nursing facility stays
Chemotherapy and other higher-cost treatments
Specialist visits in some plan types
Care from out-of-network providers
Home health care. In 2024, 90% of Medicare Advantage enrollees were in a plan that required prior authorization for it.
Certain Part D drugs, which have their own approval process

Emergency care never needs approval in advance. If you are unsure whether something is an emergency, go to the nearest emergency room and sort out coverage afterward.

How common are denials?

The volume is large. In 2024, Medicare Advantage insurers made nearly 53 million prior authorization determinations, and 7.7% of requests were denied in full or in part. That sounds small, but across tens of millions of requests it adds up to millions of denied or partly denied services.

Two findings matter most if you are weighing a plan.

Some denials are for care Original Medicare would cover. The HHS Office of Inspector General reviewed a sample of denied requests and found that 13% met standard Medicare coverage rules, meaning Original Medicare would likely have approved them.
Few people fight back, and those who do often win. Denials are rarely appealed, but the overturn rate for Medicare Advantage is 67% when they are. That pattern suggests many initial denials come from missing paperwork or automated review, not a real lack of medical need.

The experience also depends heavily on which private insurer runs your plan. Two neighbors in Deschutes County with different Advantage plans can have very different experiences for the same surgery.

The 2026 timelines your plan must follow

Federal rules now put clock limits on the plan. Under CMS’s prior authorization rule, as of 2026:

Request type	Decision deadline for medical services
Standard	7 calendar days
Expedited (delay could seriously harm your health)	72 hours

If your doctor asks for an expedited review, they are saying that waiting could put your life, health or ability to regain function at risk. Ask them to mark it that way when it is true.

These deadlines apply to medical services. Part D drugs follow separate rules, so ask your pharmacist or plan how a drug approval request is handled.

What to do when a request is denied

A denial letter is not the end. Medicare’s own appeals booklet lays out the path.

Step 1: Read the notice and note the date

You generally have 65 calendar days from the date on the denial notice to file a Level 1 appeal, called a reconsideration. Put the deadline on your calendar the day the letter arrives.

Step 2: Talk to your doctor right away

The physician is often the one who has to supply the evidence of medical necessity. Ask what the plan said was missing: a test result, a note about failed earlier treatments, a specific diagnosis code. A short letter of support from your doctor often carries more weight than anything you can write yourself.

Step 3: File the appeal, fast if your health is at risk

A standard pre-service reconsideration must be decided within 30 days. If waiting could jeopardize your health, ask for an expedited appeal, which the plan must decide within 72 hours when it agrees the standard timeline is risky.

Standard and expedited appeal deadlines compared

Step 4: Ask for your case file

Requesting a copy of the case file can help you see why the plan said no. Some plans charge a fee for it, so ask about cost first.

Step 5: Know what happens next

If the plan upholds its denial, the case is forwarded automatically to an Independent Review Entity for a Level 2 appeal. You do not have to restart anything. The appeals booklet also describes later levels if you still disagree.

Be aware that a peer-to-peer conversation in the appeal may involve a reviewer who is not practicing and may not share your doctor’s specialty. If that happens, ask your doctor to put the clinical reasoning in writing.

Does Original Medicare have prior authorization too?

Yes, but narrowly. Original Medicare requires it for a short list of items, such as certain outpatient hospital services and non-emergency ambulance transport. A new test program called the WISeR model began on January 1, 2026, and applies in six states: Arizona, New Jersey, Ohio, Oklahoma, Texas and Washington. Oregon is not on that list, so Original Medicare enrollees in Bend are not covered by that test.

That is the practical difference. With Original Medicare, most covered care does not need advance approval. With Medicare Advantage, approval is built into the plan.

Is Medicare Advantage still right for you?

Plenty of people are happy with Advantage plans, especially those who value low premiums and extras. The trade-off is that you accept a plan’s network and its approval rules. Ask these questions before you enroll, or at your next annual review:

Which services on the plan’s prior authorization list matter to you? Check hospital stays, specialist referrals, home health and any drug you take.
Are your doctors and your preferred hospital in the network?
What is the maximum out-of-pocket cost if a denial leaves you with a bill?
How does the plan’s performance compare? Ask your agent or the plan for specifics rather than relying on star ratings alone.

If you are already in a plan and get approved for a treatment, keep a copy of the approval. For people in special needs plans, Medicare says an approval must stay valid for as long as the treatment is medically necessary, and the plan cannot ask for additional approvals for that treatment. Ask your own plan how it handles ongoing treatment.

Our perspective: why we talk about this before you enroll

Most people first hear about prior authorization when something has already gone wrong. A scan is delayed, or a rehab stay is cut short. We would rather you learn it at the kitchen table than in a hospital hallway.

Our approach at Mountain Top Insurance is education first. When someone in Central Oregon comes in approaching 65, we do not start with a plan recommendation. We start with how Medicare works: what Parts A, B, C and D do, which deadlines apply to you, and what trade-offs sit behind each choice. Advantage plans and Medigap policies handle approvals very differently, and that difference should be part of the decision, not a surprise afterward.

We also see people who chose an Advantage plan years ago and now want more freedom to choose doctors and fewer approval steps. For them, the question is whether a switch is possible and what it will cost. Our job is to lay out the options, including staying put when that is the right answer, and to be honest about timing. The right choice is the one you understand and can live with. We do not push one.

— Jesse Zimmerman

Medigap and the Oregon Birthday Rule: a different route

A Medigap (Medicare Supplement) policy works alongside Original Medicare. Because you stay in Original Medicare, you generally avoid the plan-level approval layer described above. Medigap has its own tradeoffs, mainly a monthly premium, so it is a decision to price out carefully.

If you already have a Medigap policy and feel you pay too much, Oregon has a useful protection. Under the state’s Birthday Rule, your window opens 30 days before your birthday and closes 30 days after. During that window you can switch to a policy with the same or lesser benefits, and the switch is guaranteed regardless of your health. The rule applies to Medicare Supplement policies issued after January 1, 1990, and does not apply to self-funded employer group plans.

Two cautions from the state’s fact sheet: moving mid-year between two Plan F High Deductible policies restarts the deductible under the new carrier, so check your timing.

We explain the mechanics in our guides to the Oregon Birthday Rule and switching Medigap plans in the 60 day window. If you are comparing policy types, our Medicare Supplement plans page is the place to start.

Medigap and the Oregon Birthday Rule: a different route — overview diagram

Leaving an Advantage plan

If you are in Medicare Advantage and want to go back to Original Medicare, the timing matters, and so does Medigap eligibility. Medigap underwriting can apply when you did not buy it during your first window, which is why the order of steps matters. Our overview of the Medicare Advantage disenrollment period in Central Oregon walks through it, and our note on Medigap and preexisting conditions covers what to expect if you apply outside a guaranteed window.

Work with a local agent who explains before enrolling

If you want a second set of eyes on how a plan handles approvals, or you want to know whether the Birthday Rule can lower what you pay, we offer free consultations in person and remotely. We help with Medicare enrollment and with an annual plan review, where we compare your current plan against your doctors, prescriptions and expected care. There is no cost to talk, and you are under no obligation to enroll through us. You can also start at our home page to see everything we offer.

Practical habits that prevent approval headaches

A few routines make life easier under any plan with prior authorization.

Ask before scheduling. When your doctor recommends a procedure, ask the office whether it needs approval and who is submitting it.
Get the approval in writing. Keep the authorization number, the dates it covers and the facility it names.
Track the deadline. If you hear nothing within the plan’s timeline, call the plan and ask for the status.
Keep your own records. Save denial letters, dates and the names of people you spoke to.
Appeal anything you think was wrong. The odds look better than most people assume.

The burden on doctors is real. In an American Medical Association survey, 88% of physicians described the burden as high or extreme. Patients who stay in touch with the office, politely and consistently, tend to see requests move along sooner.

FAQ

Can Medicare Advantage plans require prior authorization?

Yes. Plans can require it for many services, and nearly all enrollees are in a plan that does. The list of services differs by plan, so read your Evidence of Coverage or ask the plan directly.

How long does a Medicare Advantage plan have to decide?

As of 2026, seven calendar days for standard requests and 72 hours for expedited ones for medical services. Ask your doctor to request expedited review only when waiting could harm your health.

Does Oregon Original Medicare require prior authorization in 2026?

Only for a limited set of services. The new WISeR test program runs in six other states, and Oregon is not among them. Most care under Original Medicare does not need advance approval.

How long do I have to appeal a denial?

You have 65 calendar days from the date on the denial notice to file a Level 1 appeal. If the plan upholds its decision, the case moves automatically to an Independent Review Entity. Talk to your doctor the same week the letter arrives.

Can I switch to Medigap if I dislike prior authorization?

Sometimes. Your eligibility depends on your timing and, in some cases, your health history. Oregon’s Birthday Rule helps people who already hold a Medigap policy, but it does not guarantee entry for someone coming from an Advantage plan. A free conversation with a local agent can tell you where you stand.