Medicare does require prior authorization for some services, but not all

Prior authorization means your doctor or hospital must get approval from Medicare (or your Medicare plan) before you receive certain treatments, procedures, or equipment. Medicare Part A and Part B do require prior authorization for some services — mainly inpatient hospital stays, certain surgeries, and durable medical equipment like wheelchairs or oxygen. If you have a Medicare Advantage plan (Part C), your plan's rules about prior authorization may be stricter than Original Medicare's rules.

The key difference is this: Original Medicare (Part A and Part B) requires prior authorization mainly to protect you from unexpected costs and to make sure the service is medically necessary. Medicare Advantage plans use prior authorization more often as a way to manage which providers and treatments they cover. Your doctor's office usually handles the prior authorization request — you do not have to do it yourself, though you should know it is happening.

Key Takeaways

  • Original Medicare requires prior authorization for inpatient hospital stays, certain surgeries, and durable medical equipment, but not for most office visits or outpatient services.
  • Medicare Advantage plans have their own prior authorization rules that vary by plan and may be more restrictive than Original Medicare.
  • Your doctor's office typically submits the prior authorization request and should tell you whether one is needed before your appointment.
  • If prior authorization is denied, you have the right to appeal the decision and request a review.

What services require prior authorization under Original Medicare

Inpatient hospital stays almost always need prior authorization. If you are admitted to the hospital for more than a few days, Medicare will review whether the stay is medically necessary and whether you truly need to be an inpatient rather than receiving care as an outpatient. Your hospital will handle this request, usually before or shortly after you arrive.

Certain surgeries and procedures require prior authorization, particularly those that are expensive or less common. Examples include joint replacement, cardiac procedures, and some cancer treatments. Your surgeon's office will know whether your specific procedure needs authorization and will submit the request before your surgery date.

Durable medical equipment — wheelchairs, oxygen equipment, continuous positive airway pressure (CPAP) machines, and similar items — requires prior authorization. Your doctor must document that the equipment is medically necessary, and Medicare will review the request. This process usually takes a few days to a couple of weeks.

Skilled nursing facility stays require prior authorization. If you need rehabilitation or skilled care after a hospital stay, Medicare will review the request to confirm you need that level of care. Your hospital discharge planner or the nursing facility will submit this request.

How prior authorization works with Medicare Advantage plans

Medicare Advantage plans (also called Part C) are required by law to cover everything Original Medicare covers, but they can impose their own rules about how you access that care. Many Medicare Advantage plans require prior authorization for services that Original Medicare does not require it for — such as specialist visits, imaging like MRI or CT scans, or certain medications.

Each Medicare Advantage plan sets its own prior authorization rules. One plan might require prior authorization for physical therapy while another does not. When you enroll in a Medicare Advantage plan, you receive a document that lists which services need prior authorization. Your plan's website also lists this information, and you can call your plan's customer service line to ask about a specific service.

Your doctor's office should know your plan's rules and submit prior authorization requests on your behalf. However, it is worth confirming with your plan directly before a scheduled procedure, especially if it is expensive or time-sensitive. If your doctor's office is not in your plan's network, the responsibility to request prior authorization may fall on you.

What happens when your doctor requests prior authorization

When your doctor's office submits a prior authorization request, they send Medicare (or your plan) clinical information about why you need the service. This includes your diagnosis, test results, previous treatments you have tried, and why this particular service is the right next step. Medicare or your plan reviews this information to decide whether it meets their criteria for medical necessity.

The review usually takes a few business days, though urgent requests can be reviewed within 24 hours. Your doctor's office will contact you once they hear back. If the request is approved, you can move forward with your appointment or procedure. If it is denied, your doctor will discuss the reason with you and may appeal the decision or suggest an alternative treatment.

You should not have to pay out of pocket for a service that has been approved through prior authorization. If you receive a bill for an authorized service, contact your plan or Medicare to dispute it. Keep copies of the prior authorization approval in case questions come up later.

What to do if prior authorization is denied

If Medicare or your plan denies a prior authorization request, you have the right to appeal. Your doctor can request a reconsideration, which means Medicare or your plan will review the decision again, usually with additional clinical information your doctor provides. This reconsideration is often successful if your doctor can provide more detail about why the service is necessary.

If the reconsideration is also denied, you can request a formal appeal. The appeal process varies depending on whether you have Original Medicare or a Medicare Advantage plan, but both allow you to present your case in writing and, in some cases, in person. Your doctor can help you gather the medical evidence needed for the appeal.

While your appeal is being reviewed, you can ask for a "continuance of benefits," which means you can receive the service while the appeal is pending. This protects you from being denied care during the review process. Ask your doctor or plan how to request this.

How to learn about a specific service needs prior authorization

The simplest way is to ask your doctor's office directly. When you schedule an appointment or procedure, tell them you have Medicare and ask whether prior authorization is needed. They will know the answer and can tell you how long the process typically takes.

If you have Original Medicare, you can also call Medicare directly at 1-800-MEDICARE (1-800-633-4227) to ask whether a specific service requires prior authorization. Have your diagnosis and the name of the procedure ready when you call.

If you have a Medicare Advantage plan, call your plan's customer service number (on your insurance card) and ask about prior authorization for your specific service. You can also check your plan's website, which usually has a list of services that require prior authorization.

Do not wait until the day of your appointment to ask. Prior authorization requests can take time, and submitting early gives you the best chance of having approval before your scheduled date.

Frequently Asked Questions

Do I have to pay for prior authorization?

No. Prior authorization is a review process, not a service you pay for. Your doctor's office submits the request at no cost to you. If Medicare or your plan approves the service, you pay only your normal copay, coinsurance, or deductible — the same amount you would pay without prior authorization.

What if my doctor's office forgets to request prior authorization?

If you receive a service without prior authorization when one was required, you may receive a bill. Contact your doctor's office and ask them to submit the prior authorization request retroactively. Many times, Medicare or your plan will approve it after the fact and cover the service. If they do not, ask about appealing the denial.

Does prior authorization delay my care?

It can add a few days to a week, depending on the service and how quickly your doctor's office submits the request. Urgent requests are reviewed faster — sometimes within 24 hours. If you need care quickly, tell your doctor's office so they can mark the request as urgent and explain the time-sensitive nature to Medicare or your plan.

Can I go to any doctor for a service that needs prior authorization?

If you have Original Medicare, yes — you can see any doctor who accepts Medicare. If you have a Medicare Advantage plan, your doctor usually must be in your plan's network for the prior authorization to cover the service. Check your plan documents or call your plan to confirm your doctor is in-network before scheduling.

What is the difference between prior authorization and a referral?

A referral is a recommendation from your primary care doctor to see a specialist. Prior authorization is Medicare's approval that a service is medically necessary and covered. Some services need both — your primary care doctor refers you to a specialist, and then prior authorization is requested to confirm coverage. Original Medicare does not require referrals, but Medicare Advantage plans often do.