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Medicare Prior Authorization Explained

Before your doctor can provide specific services, prior authorization from Medicare may be necessary. Depending on your plan type, you might need prior approval to see a specialist.

So, which services and types of plans require prior authorization? Below, we’ll explain what you need to know.

What is Prior Authorization for Medicare?

Prior authorization means your doctor must get approval before providing a service or prescribing a medication. Now, when it comes to Advantage and Part D, coverage is often plan-specific. Meaning, you should contact your plan directly to confirm coverage.

Medicare Part A Prior Authorization

Medicare, including Part A, rarely requires prior authorization. If it does, you can obtain the forms to send to Medicare from your hospital or doctor. The list mostly includes durable hospital equipment and prosthetics.

Medicare Part B Prior Authorization

Part B covers the administration of certain drugs when given in an outpatient setting. As part of Medicare, you’ll rarely need to obtain prior authorization.

Although, some meds may require your doctor to submit a Part B Drug Prior Authorization Request Form. Your doctor will provide this form. Once the request gets approval, coverage begins.

Also, CMS has added specific cosmetic procedures to the list of outpatient care. The goal is to prioritize medically necessary procedures.

Medicare Part D Prior Authorization

Often, even top Part D prescription drug plans need prior authorization for coverage on specific drugs. Different policies have varying rules, so you’ll need to contact the carrier directly to confirm coverage.

Most Part D plans have forms you can download online. The online option is a useful way to print the documents and take them to your doctor. Your doctor can help you correctly complete the form.

Also, recipients may directly contact their Part D plan and ask for a mail-in form. You can find the number for Member Services on your plan’s member ID card.

Medicare Advantage Prior Authorization

To obtain out-of-network, specialist, and emergency care, Medicare Advantage recipients may need prior authorization. Unfortunately, if Medicare doesn’t approve the request, the Advantage plan typically doesn’t cover any costs, leaving the full cost to you.

Reports have shown that as many as four out of five members with Advantage plans require prior authorization for certain services. The services most often requiring prior approval are durable medical equipment, skilled nursing facility stays, and Part B drugs.

But, each Advantage plan is different. If you have an Advantage plan, contact your plan provider to determine if or when prior authorization is necessary. Your plan will have forms you can download online.

Also, Advantage members may appeal to their plan’s denial. Yet, most don’t take advantage of this.

How Do I Get Prior Authorization for Medicare?

Refer to your plan documents, including the drug formulary, to see if your treatment requires approval. This information should be on your plan’s website. The Medicare & You handbook also contains more information.

Your provider is responsible for requesting permissions. Be sure to give them all the information they need for submission, ensuring it’s correct. Double-check your plan’s terms as well.

If your provider believes your treatment is medically necessary, they can contact your plan and request an exception if you get denied. The provider must support the request with a statement. Once approved, your plan pays without prior authorization.

How Long Does it Take to Get Prior Authorization?

It can take days to get prior authorization. Although, if you’re waiting for a drug, you should call your local pharmacy within a week.

Sometimes, permission is either denied or delayed. If this happens, contact your insurance provider to ask why.


Does Medicare require prior authorization for MRI?
If the purpose of the MRI is to treat a medical issue, and all providers involved accept Medicare assignment, Part B would cover the inpatient procedure. An Advantage beneficiary might need prior authorization to visit a specialist such as a radiologist.
Does Medicare require prior authorization for a CT scan?
If your CT scan is medically necessary and the provider(s) accept(s) Medicare assignment, Part B will cover it. Again, you might need prior authorization to see an out-of-network doctor if you have an Advantage plan.
How do I get Medicare prior authorizations for a therapy regimen?
You’ll get prior authorization the same way, no matter the service. Your doctor will document medical necessity and send forms to either Medicare or your plan for approval.

Getting Help Understanding Prior Authorization

This information can seem overwhelming, and things are always changing. Our goal is to keep you informed to help you pick the best coverage for you. We can start helping by comparing rates in your area.

Call the number above to talk to an agent. Or fill out our online rate form to see costs.

Lindsay Malzone

Lindsay Malzone is the Medicare expert for MedicareFAQ. She has been working in the Medicare industry since 2017. She is featured in many publications as well as writes regularly for other expert columns regarding Medicare. You can also find her over on our Medicare Channel on YouTube as well as contributing to our Medicare Community on Facebook.

10 thoughts on “Medicare Prior Authorization Explained

    1. Hi Joyce! If you have Original Medicare Part A & Part B only, no. If you have a Medicare Advantage plan, it’s up to the carrier if they require prior authorization.

  1. We just received a bill for $160,000 for a one-day procedure that was pre-authorized. Our insurance company says that Medicare won’t pay it, so the whole bill is on us even though we got pre-authorization. What is the use of pre-authorization if the bill isn’t going to be at least partially paid by Medicare?

    1. Hi Virginia. This sounds like a billing error. Your best option is to do a three-way call between the billing department and Medicare to have this resolved ASAP.

  2. My husband had an AVM 20 years ago. Ten years later a large cyst developed at site which required surgery. He has had small non-verbal seizures since then until 2 weeks ago. The last 2 caused confusion for an hour. It has been 11 days since doctor ordered MRI but we are waiting on prior authorization. Should it take that long?

    1. Hi Marilyn! Unfortunately, this is one of the many downfalls of Medicare Advantage plans. You should be able to log into your online portal either through the Advantage carrier or Medicare to see the status of your prior authorization. But yes, it can take this long depending on the carrier you enrolled with.

  3. I am inquiring if medicare is primary and patient has medicare supp as secondary and it follows medicare guidelines, is the medicare authorization used for the supplement coverage too or does a separate auth have to be obtained?

    1. Hi Maria! A Medicare Supplement policy will always cover anything Medicare overs. If Medicare approved the service or procedure and required a prior authorization form, the Medigap plan will NOT require an additional prior authorization form. I hope this helps!

  4. Lindsay I work in the health care field and come across unique situations. Can I reach out to you via email for questions?


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