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What is prior authorization in Medicare, and what to do if it’s denied

Some care needs a yes from Medicare or your plan before you get it. Here is how that works, how long it should take, and what you can do when the answer is slow or no.

Last reviewed September 27, 2026

What does prior authorization mean?

It means getting approval before the care, rather than finding out afterwards whether it’s covered. The approval doesn’t mean the care is needed or not needed. It’s a decision about payment.

In most cases the request comes from the doctor, hospital or equipment supplier, because they have the medical records the plan wants to see. Your part is usually to make sure it has been sent, and to follow up if it stalls.

You may also hear it called pre-approval, pre-authorization, or “prior auth”. In a Medicare Advantage plan (a private plan that replaces Original Medicare), the official name for the plan’s decision is an organization determination. You or your doctor can ask for one, by phone or in writing.

Source: Medicare.gov, appeals in a Medicare health plan; 42 CFR 422.566 and 422.568.

Does Original Medicare require prior authorization?

Rarely. Medicare says that in most cases you don’t need approval for Original Medicare to cover your care. The exceptions are a short list of services and items, and a newer program in six states.

Some hospital outpatient procedures. Anywhere in the country, the hospital must get approval first for eyelid surgery (blepharoplasty), botulinum toxin (Botox) injections, removal of excess belly skin (panniculectomy), nose surgery (rhinoplasty), vein ablation, implanted spinal nerve stimulators, neck fusion with disc removal, and facet joint injections for back pain.

Some medical equipment. Medicare keeps a Required Prior Authorization List for equipment. It includes many power wheelchairs and scooters, some pressure-relieving mattresses, some leg prostheses and braces, and some compression devices. CMS added items in April 2026 and is adding more, so the supplier is the one to ask.

For both of these, Medicare’s reviewer should decide within 7 calendar days, or 2 business days when the request is expedited (marked urgent).

Source: CMS, prior authorization for hospital outpatient services; CMS, prior authorization for medical equipment; Medicare.gov, compare Original Medicare and Medicare Advantage.

What is the WISeR model?

WISeR is a six-year Medicare test, running from January 1, 2026 to December 31, 2031, that adds prior authorization for a set list of services in Original Medicare. It covers six states: Arizona, New Jersey, Ohio, Oklahoma, Texas and Washington. It does not apply to Medicare Advantage.

These are the services on the list:

• Certain implanted nerve stimulators, including ones for bladder control, breathing, sleep apnea and the vagus nerve
• Procedures that deaden nerves to treat pain
• Epidural steroid injections for pain
• Vertebral augmentation for spine fractures
• Neck (cervical) fusion
• Knee arthroscopy for osteoarthritis
• Incontinence control devices and treatments for erectile dysfunction
• Skin and tissue substitutes for leg wounds that won’t heal, only in the areas where local Medicare rules cover them

Deep brain stimulation and a spinal stenosis procedure called lumbar decompression were on the original list. In April 2026 CMS delayed both until a date it has not yet announced.

WISeR leaves out emergency care, and services where waiting could put you at serious risk. Your doctor, hospital or supplier chooses either to ask for approval first, or to go ahead and have the claim reviewed before Medicare pays it. Reviewers usually decide within 3 days, or 2 days when it’s urgent. If the answer is no, your doctor must give you an Advance Beneficiary Notice (a form saying Medicare may not pay, which asks whether you still want the service) before treating you. You keep all your usual appeal rights.

Source: CMS, WISeR model; CMS, WISeR frequently asked questions; Federal Register, July 1, 2025, and April 6, 2026 delay notice.

How do Medicare Advantage plans use it?

Much more widely. Each plan sets its own list, so the same scan or surgery can need approval in one plan and not in another. The plan’s Evidence of Coverage (the long booklet that sets out your plan’s rules) says which services need it.

Since January 1, 2026, federal rules set how fast your plan must decide:

Two things to know about these limits. A Medicare Advantage plan can take up to 14 more days in a few cases, such as when it’s waiting on records. If it does, it must tell you in writing why, and you can file a fast complaint if you disagree. And if a plan misses its deadline, the silence counts as a denial, which you can appeal.

When a plan says no, it must tell you in writing, give the specific reason, and explain how to ask it to reconsider.

Emergency care is different. Your plan has to cover emergency and urgently needed care whether or not anyone got approval first.

Source: 42 CFR 422.568, 422.572, 422.122 and 422.113; CMS, Interoperability and Prior Authorization Final Rule (CMS-0057-F).

What about prescription drugs?

Part D drug plans (and Medicare Advantage plans that include drug coverage) have their own rules. A plan may need approval before it covers a drug, ask you to try a cheaper drug first (called step therapy), or limit how much you can get at once.

Asking the plan to cover a drug is called a coverage determination. The plan must answer within 72 hours, or 24 hours if waiting could harm your health.

If a rule blocks a drug you need, your prescriber can ask for an exception. That’s a request to cover a drug that isn’t on the plan’s list, to set aside a rule like step therapy, or to charge a lower price tier. Your prescriber has to send a statement explaining the medical reason. The 72-hour or 24-hour clock starts when the plan receives that statement, so ask the office to send it the same day.

The 7-day and 72-hour limits in the section above don’t apply to drugs. The drug rules are separate.

Source: Medicare.gov, drug plan rules; Medicare.gov, appeals in a drug plan; 42 CFR 423.568, 423.572 and 423.578.

What happens to an approval if you switch plans?

You’re protected for a while, but not forever. Plan ahead before your new coverage starts.

Medicare Advantage. If you join a new plan partway through a course of treatment, the new plan must give you at least 90 days without making you get approval again. That applies even if your doctor is outside the new plan’s network. Within one plan, an approval for a course of treatment has to last as long as it’s medically needed.

Drugs. In the first 90 days of a new drug plan, you can get a one-time temporary supply (at least a month’s worth) of a drug you already take, even if the new plan doesn’t cover it or needs approval for it. The plan must then write to you. Use that month to have your prescriber ask for an exception or switch drugs.

Source: 42 CFR 422.112(b)(8); 42 CFR 423.120(b)(3); Medicare.gov, drug plan rules.

What to ask, and in what order

Most delays happen because a request was never sent, was sent incomplete, or is waiting on one missing record. These steps work through those in order.

1. Call your doctor’s office. Ask: Did you send the prior authorization request? On what date? Which number did you send it to? Is anything missing? Write down the date and the name of the person you spoke to.
2. If it’s urgent, ask for an expedited decision. If waiting could seriously harm your health or your ability to recover, ask the doctor to mark the request as expedited. When a doctor says it’s urgent, a Medicare Advantage plan must treat it that way. You can ask too, but the plan then decides for itself.
3. Call your plan. Use the member services number on your card. Ask: Have you received a prior authorization request for [service] from [doctor]? What is the status? What date is the decision due? Ask for a reference number.
4. If the deadline passes, say so. Tell the plan the deadline has passed and ask for the decision. A missed deadline counts as a denial, and you can appeal it.
5. If it’s denied, read the letter. It must give the specific reason. Many denials are about missing paperwork, and your doctor can fix those by sending more records or talking with the plan’s reviewer.
6. Ask for a reconsideration. In Medicare Advantage, that’s the first step of an appeal: the plan looks at its decision again. The deadline is printed on the denial letter, so don’t wait. Our guide to [what to do when Medicare denies a claim](What to do when Medicare denies a claim) covers every step after that.

For Original Medicare, including WISeR, call 1-800-MEDICARE (1-800-633-4227) if you aren’t sure who to ask.

Common questions

Is prior authorization the same as a referral?
No. A referral is your main doctor sending you to a specialist. Prior authorization is your plan approving a specific service. Some Medicare Advantage plans require both.

Can I ask for prior authorization myself?
In Medicare Advantage, yes. You can ask the plan for an organization determination before you get a service. It usually goes faster when the doctor sends it, because the plan will want their records.

Can the plan change its mind after it approves something?
Once a Medicare Advantage plan has approved a service in advance, it can’t later refuse to pay on the grounds that it wasn’t medically necessary. The only exceptions are good cause, such as new evidence, or fraud.

Do I need approval for emergency care?
No. Medicare Advantage plans must cover emergency and urgently needed care whether or not anyone got approval first. Call 911 when you need to.

I live in a WISeR state. Do I need to do anything?
Usually not. It’s the doctor, hospital or supplier who sends the request. If you’re asked to sign an Advance Beneficiary Notice, it means the service may not be covered. Ask why before you sign.

Will this get easier to track?
Starting January 1, 2027, Medicare Advantage plans may handle requests electronically, and you may be able to see decisions in your plan’s online portal.