Prior authorization is the process by which your doctor must request approval from your Medicare plan before they can order a particular medication or medical service.
Generally, Original Medicare (parts A and B) rarely asks for prior authorization because most medical care is preapproved. Prior authorization tends to be more common with Part C (Medicare Advantage) and prescription drug plans (Part D).
Read on to learn about how prior authorization works in Medicare and when you need it.
It’s less common for Original Medicare to ask for prior authorization than it is for Part C or Part D plans. These plans tend to ask for prior authorization as a way to make sure your treatment is medically necessary and, in this way, manage costs.
In most cases, your Medicare Part C or Part D plan will cover your treatment only if it receives prior authorization.
In addition to prior authorization for specific treatments, Part C plans might also ask for prior authorization before you see a specialist doctor, get care outside of your plan’s network, or go to the hospital for care that isn’t an emergency.
In Medicare Part D, prior authorization is called a coverage determination. Specifically, in the case of Part D, prior authorization may also involve a process known as step therapy. This requires you to try a less costly medication before you can be approved for coverage of a costlier one.
Since private insurers manage Part C and D plans, each has different rules about where to ask for prior authorization. To understand the specific rules of your plan, you’ll need to contact your plan provider directly.
There isn’t a specific form your healthcare professional needs to fill out to request prior authorization. They can submit their request directly to Medicare by fax or mail, through the electronic submission of medical documentation, and via Medicare administrative contractor (MAC) electronic portals.
MACs are the Medicare agents who review these requests. They may provide different types of responses:
- Provisional affirmation decision: This suggests that a future Medicare claim for the item or service likely meets the necessary coverage, coding, and payment requirements.
- Nonaffirmation decision: This indicates that the claim does not meet the requirements.
- Provisional partial affirmation decision: This means that some services on your doctor’s request received a preliminary affirmation while others did not.
Once a MAC has reviewed a request, they will send a written notice of its decision to your healthcare professional. If the decision is nonaffirmation, the MAC will explain why, and they will share this information with beneficiaries.
As long as the claim hasn’t been sent for payment yet, your healthcare professional can resubmit the prior authorization request as many times as they want.
What is the phone number for Medicare prior authorization?
The prior authorization process typically happens between your doctor and Medicare. While you don’t need to be involved, you can call to check the status of your prior authorization request.
Where you call depends on your plan. With Original Medicare, you can call 800-MEDICARE (800-633-4227). TTY users can contact 877-486-2048.
With Part C pr D plans, you’ll need to contact the insurers directly, usually via the customer service number on the back of your insurance plan.
With Original Medicare and Part C, prior authorization can take about 10 days. That said, to try to reduce barriers to coverage, the Centers for Medicare & Medicaid Services (CMS) has reduced this wait time to 7 days as of 2025.
If your doctor wants a quicker review, they can request an expedited process that takes up to 2 business days. Medicare may or may not approve this request.
This new policy
On the other hand, in a country where the cost of healthcare tends to be higher than in many other countries, prior authorization can help insurers keep expenses down, which could help keep your costs lower. This most often applies to drug costs but can also apply to the cost of other medical care.
Specifically, prior authorization can help support the use of preferred medications. These medications tend to be more cost effective, work better, be safer, or fit well with evidence-based treatment guidelines.
Step therapy can also help ensure that the prescribed drugs are approved by the Food and Drug Administration (FDA) for your particular needs. If you need an off-label drug, prior authorization can approve your prescription only if its effectiveness is supported by peer-reviewed scientific literature or recommended by respected medical guidelines.
Navigating prior authorization
This can be challenging because the process isn’t always clear or predictable. Often, the person reviewing prior authorization claims may not be a doctor or fully understand the care you need. As a result, time and attention can sometimes shift from your care to managing appeals.
In addition, your doctor might need to spend extra time obtaining prior authorization or helping you appeal denials, which could lead to delays in your care.
Prior authorization is less common with Original Medicare than with Part C and Part D. These plans may require it to confirm medical necessity and manage costs. Coverage typically begins only after authorization is granted.
Part C might require it for specialist visits, out-of-network care, or nonemergency hospital visits. With Part D, it’s called coverage determination and often involves step therapy, which asks you to try less costly medications first.
The prior authorization process can help manage costs by promoting safer, cost-effective medication, but it can also be complex and potentially delay treatment. To understand how prior authorization works with your plan, contact your insurer for its specific rules.