The prior authorization process, step by step

The prior authorization process, in order

Prior authorization can feel like a black box, but the sequence behind it is fixed and fairly simple to follow. Medicare sets out a specific order for how a Part D drug plan has to handle a request, and each stage has a name and, in most cases, a deadline attached to it. Here's how it actually runs, from the moment your prescriber picks up a pen to the moment the plan gives you an answer:

1. Your prescriber writes the prescription. It goes to your pharmacy as normal, and nothing about this step signals whether a review is coming.
2. The pharmacy flags the requirement. The pharmacy's system checks the drug against your plan's formulary the moment it tries to bill the claim, and returns a rejection code within seconds if prior authorization applies.
3. Your prescriber submits the request. This has to come from your prescriber's office, not you and not the pharmacist. It should include your diagnosis, relevant lab results or treatment history, and a specific clinical reason for that drug.
4. The plan opens a coverage determination. This is Medicare's formal term for the plan's review. A clinical reviewer checks the request against the plan's own coverage rules for that medicine.
5. The plan decides inside its deadline. A standard request gets 72 hours from the point your prescriber submitted it. An expedited request, used when delay could seriously harm your health, gets 24 hours.
6. You get an approval or a written denial. Approval means the pharmacy can bill the plan and you pay your normal copay. A denial comes with a notice explaining why, and exactly how to challenge it.
7. You request a redetermination if you're refused. This first appeal is decided by the plan itself, not an outside body. It must be requested within 60 days of the denial notice.
8. You escalate further if the denial stands. An Independent Review Entity looks at the case next, and cases with enough money at stake can go on to an administrative law judge, and beyond that to a Medicare Appeals Council and federal court.

How long each stage is allowed to take

This is the part that matters most once you're actually waiting. Two federal rules, 42 CFR 423.568 and 423.572, set the clock for the plan's first decision. A related rule, 423.590, sets the clock for the appeal that follows a denial. None of these are guidelines a plan can quietly stretch. If a plan sits past its own deadline, the silence itself counts as a denial, which means you can move straight to an appeal rather than waiting for a letter that may never arrive.

Two details catch people out. First, the clock for a coverage determination starts when your prescriber's office submits the request, not when the pharmacy first flagged it, so a slow fax machine at the surgery can cost you days before the plan's deadline even begins to run. Second, an expedited review isn't something you can talk your way into at the pharmacy counter. Your prescriber has to state, in the request itself, that waiting the standard 72 hours could seriously jeopardise your health or your ability to function.

A worked example: a flagged prescription in real time

It helps to see the timing laid out, so here's an illustrative example rather than a real case. Picture a rheumatologist prescribing a biologic injection after methotrexate stops controlling a patient's joint pain. On a Monday morning, the patient takes the prescription to her usual pharmacy. The pharmacy's system rejects the claim within seconds and returns a prior authorization code. That afternoon, the pharmacy's software automatically faxes a request-for-information form to the rheumatologist's surgery. By Tuesday, someone on the clinical team pulls together the relevant blood tests, the record of the failed methotrexate course, and a short clinical statement, then submits it to the plan as a standard request. The plan's 72-hour clock starts from that Tuesday submission, not from Monday's rejection at the till. By Thursday afternoon, comfortably inside the window, the plan approves the drug. The patient collects it from the pharmacy on Friday, paying only her normal copay.

Total time from prescription to approval: four working days, and every one of them sat inside the rules. Had the plan denied the request instead, the same clock would simply reset at the appeal stage, giving the surgery 60 days to file a redetermination rather than four. The speed in this example came almost entirely from the surgery having the right paperwork ready on day one. A request missing the lab results, sent back for more information, easily doubles that timeline.

What happens if the plan says no

A denial notice has to explain the specific reason for the refusal and set out exactly how to challenge it. The first step is a redetermination: an appeal decided by the plan itself, not an outside reviewer. You or your prescriber must request it within 60 days of the denial notice. The plan then has 7 calendar days to decide a standard redetermination, or 72 hours for an expedited one.

If the plan upholds its own denial, the case moves to an Independent Review Entity (IRE): a body under contract to Medicare, entirely separate from your plan, that examines the evidence afresh. Beyond that, if enough money is at stake — at least $200 for 2026 — you can request a hearing before an administrative law judge through the Office of Medicare Hearings and Appeals. A further Medicare Appeals Council review, and ultimately federal court, sit above that, though very few cases travel that far.

“Medicare Advantage insurers fully or partially denied 4.1 million prior authorization requests, which is a somewhat larger share (7.7%) of all requests than in 2023.”

That figure covers Medicare Advantage plans broadly rather than standalone Part D drug plans specifically, since insurers aren't required to break the numbers down that finely. But the appeals machinery runs on the same federal rules either way, and the same KFF analysis found that more than eight in ten appealed denials were overturned in 2024. Very few people appeal in the first place. That gap, between a low appeal rate and a high overturn rate, suggests plenty of refusals that would likely be reversed simply never get challenged.

Common mistakes that slow the process down

How to speed up your own request

You can't submit or appeal a request yourself — only your prescriber can do that — but you're not powerless while it's in progress.

• Call your prescriber's office directly rather than waiting on a fax queue. A phone call gets a request looked at sooner than a form sitting behind referral letters and test results.
• Ask what specific criteria the plan needs before anything is submitted, so a request for more information doesn't restart the 72-hour clock partway through.
• Ask your prescriber to state explicitly, in writing, if delay would seriously affect your health, so the request is treated as expedited from the outset.
• Keep a copy of every denial notice and its date. The 60-day appeal clock runs from that date, not from whenever you happened to notice it.
• If you're refused, ask the pharmacy to check whether a different strength or formulation of the same drug carries fewer restrictions while the appeal is pending.