Your insurer said no, but the process has built-in second chances. Here is what to do first, which deadlines apply and where to find free help with your appeal.

This guide is general information, not insurance, tax or legal advice. Rules, limits and deadlines change each year, so check HealthCare.gov, Medicare.gov or your insurer for your situation.

Getting word that your insurer will not approve the scan, procedure or drug your doctor ordered is discouraging, but a prior authorization denial is a starting point, not a verdict. Denials happen for many reasons, from a missing form to a disagreement over medical judgment, and each reason points to a different next step. Here is what to do, roughly in order, starting the day the denial arrives.

A Denial Isn’t a Final Answer

These denials are common. A KFF analysis of 2023 Medicare Advantage data found that about 6.4 percent of prior authorization requests in those plans were denied, and many were later overturned on appeal. More broadly, among insured adults, 7 in 10 describe prior authorization as a burden on their health care, so if you are dealing with one right now, you are in familiar company.

The process also has built-in second chances. You can ask your insurer to reconsider through an internal appeal, and if that fails, many plans allow an external review by an independent third party. Once a case goes to external review, an outside reviewer weighs the evidence and the plan has to go along with the outcome. If the whole system feels opaque, our explainer on prior authorization covers the reasoning behind these approval requirements and how the process works.

Get the Denial Reason in Writing

The plan is required to send you written notice explaining its decision, and when you are seeking prior authorization that notice is due within 15 days. Under a federal rule that takes effect in 2026, Medicare Advantage, Medicaid, CHIP and exchange plans, together with their managed care plans, must cite the specific reason a prior authorization was turned down. Other plans still have to tell you why, though the letter may be brief.

Go through the denial letter and your Explanation of Benefits line by line, because the stated reason tells you what kind of evidence will fix the problem. A denial for missing documentation calls for records. A denial saying the treatment is not medically necessary calls for a clinical justification from your doctor. When the letter does not name the criterion, call the plan, ask what standard the request failed to meet, and get that answer confirmed in writing.

Call Your Insurer and Take Notes

A phone call can answer what the letter leaves out. Ask the representative exactly which requirement was not met, whether the problem was administrative or clinical, and what the deadline is to request reconsideration or file an appeal. Write down the day, time, name and title of every person you speak with, along with what was said, and keep any reference or case numbers. Put the appeal deadline on your calendar the day the denial arrives, not the week it is due.

Fix Paperwork Problems First

Not every denial is a disagreement about medicine. Check first whether it was administrative: an incorrect member ID, a billing code that does not match what was requested, a form nobody filled in, or paperwork routed to the wrong payer or vendor. Mistakes like these are typically resolved by fixing the error and sending the request again, not by appealing. And when a denial traces back to missing details, supplying them often turns the decision around before any appeal is needed.

Requests most often get turned down because records are missing, details are wrong, the plan restricts the coverage, or the file does not adequately document medical necessity. An approval does not close the book, either. Claims can still be denied afterward over coding errors, documentation gaps or a date of service outside the authorization window, so keep the approval number and its details on file.

If you went ahead with care and are now facing a bill for it, our guide to surprise medical bill mistakes covers that situation.

Ask Your Doctor About a Peer-to-Peer Review

When a denial turns on clinical judgment, the most direct fix is a conversation between your doctor and the plan’s medical reviewer, called a peer-to-peer review. Your doctor explains the case directly to another physician, who can reconsider the decision. Ask your doctor’s office to request one promptly, because many plans offer it only during a short window after the denial.

Even if no call happens, ask your doctor for a letter that speaks directly to the insurer’s stated reason: what you have been diagnosed with, the medical support for this particular treatment, and the risk of going without it. Records that back up those points make the letter harder to dismiss. You can also authorize your doctor or another representative to file the appeal for you, and the plan will require a signed form naming that person.

File a Formal Appeal, and Know Your Deadlines

An internal appeal asks the insurer to reexamine its decision with a complete review of the record. Complete the forms the plan requires, or simply write a letter that includes your name, claim number and insurance ID number. Then submit anything the insurer did not have the first time, such as your doctor’s letter or additional records. Our article on mistakes to avoid when appealing a denied health claim walks through the errors that sink otherwise strong appeals.

Deadlines vary by situation, and they are firm:

Situation	Timeframe
Written notice of a prior authorization denial	Within 15 days of the request
Internal appeal for a service you have not received yet	Completed within 30 days
Internal appeal for a service you already received	Completed within 60 days
Medicare Advantage standard reconsideration	File within 60 calendar days of the denial notice
Written request for external review	Within 4 months of the final denial

Employer plans governed by ERISA have to allow a minimum of 180 days for you to appeal an adverse benefit determination. When the internal appeal ends, the insurer must send you a written decision. If it still denies the service, you can request an external review, in writing, within 4 months after the date you receive that final determination.

External review covers three kinds of denials: those resting on medical judgment where you or your doctor disagree with the plan, those labeling a treatment experimental or investigational, and cancellations of coverage that the insurer justified by saying you gave false or incomplete answers on your application. The independent reviewer weighs the case and comes back with a final call, one the insurer is required by law to accept. Keep your originals and submit copies of everything you send.

Important: External review requests are due within 4 months of the insurer’s final internal denial. Jot down that date the moment the letter comes, because a late request will not be accepted.

Expedited Appeals When Time Matters

If waiting for a standard decision would put your health at serious risk, ask for an expedited appeal, and the insurer must speed up the process. For Medicare Advantage, Medicaid and CHIP plans, federal rules set a maximum of 72 hours for an urgent prior authorization decision and seven calendar days for a standard one. Medicare Advantage plans handling urgent requests must act as quickly as the patient’s condition demands, with 72 hours as the outside limit for items and services. These clocks run in calendar time, not business hours: a request received at 1:00 AM on a Sunday must be answered by 1:00 AM on the following Wednesday.

Where to Get Free Help: Your State and Medicare

You do not have to manage this alone. Many states run Consumer Assistance Programs that help people with health insurance problems by phone, postal mail, email or in person, and staff at the program in your state can file an appeal on your behalf. Where no program exists, the same official resources point you to alternatives such as your state Department of Insurance and the US Department of Labor.

For external review, the information on your Explanation of Benefits or the final denial of your internal appeal should include contact details for the organization that handles it. If your plan uses the federal external review process, you can request a form by calling MAXIMUS Federal Services toll free at 1-888-866-6205. State processes differ, so check your denial letter or your state insurance department. If you have Medicare, Medicare.gov explains how appeals work in that program.

Start today: pull out the denial letter, mark the appeal deadline on your calendar, and call your doctor’s office about requesting a peer-to-peer review.

Frequently asked questions

What is a peer-to-peer review?
It is a phone call between your doctor and the medical reviewer who denied the request, so your doctor can explain the clinical case directly. Many plans offer it only during a short window after the denial, so ask promptly.

What if my prior authorization was approved but the claim is still denied?
Approval does not guarantee payment. Claims can still be denied for coding errors, documentation gaps or a date of service outside the authorization window, so keep your approval details and ask your provider to correct and resubmit.

How fast must my insurer decide an urgent request?
Federal rules for Medicare Advantage, Medicaid and CHIP plans set a maximum of 72 hours for urgent prior authorization decisions and seven calendar days for standard ones, measured in calendar time rather than business hours.

Who can help me appeal for free?
Many states run Consumer Assistance Programs that can file an appeal for you by phone, mail, email or in person. Where no program exists, official resources point you to your state Department of Insurance and the US Department of Labor.