Quick answer: a prior authorisation denial means the plan refused payment, usually because approval was missing, incomplete, expired, or did not match the service actually provided. In US spelling, this is a prior authorization denial, and the focus keyword for this guide is prior authorisation denial. Before you appeal, check five things in order: whether authorization was required at all, whether it was obtained, whether it covered the exact service, provider, and dates, whether the documentation supports medical necessity, and whether the appeal deadline and channel are correct. Appealing without those checks wastes the appeal window.
What prior authorization is, and what it is not
Prior authorization, also called preauthorization or prior approval, is a plan decision before care that a service, test, procedure, or medicine is medically necessary under the plan rules. HealthCare.gov defines preauthorization in those terms, and adds an important caution: preauthorization is not a promise that the plan will pay. Coverage, eligibility on the date of service, coding, and documentation still matter after approval.
Plans commonly require authorization for imaging such as MRI, certain surgeries, specialty medicines, durable equipment, physical therapy beyond an initial set of visits, and some genetic tests. Routine primary care visits and many basic labs usually do not require it, but the list varies by plan, by service, and sometimes by diagnosis, so never assume. The plan benefit document and the provider office are the sources for your plan, not a general list on a website.
The pre appeal checklist, in order
Work through this checklist before drafting an appeal, because each item points to a different fix.
- Was authorization required. Check the plan benefit document, the EOB remark, and the denial letter. If authorization was not required, the denial reason may be miscoded, and a phone correction may be faster than a formal appeal.
- Was authorization obtained. Ask the provider office for the authorization number, the approval date, and the approved service. If no authorization exists, ask whether one can still be obtained retroactively, or whether the service needs to be rescheduled with authorization in place. Some plans allow retroactive review in limited circumstances, such as urgent care, but many do not.
- Did the approval match what was done. Compare service, provider, facility, diagnosis, and dates. An approval for one imaging study does not cover a different study. An approval for one provider does not cover another provider. An approval that expired before the service date does not cover that date. A mismatch here is often fixed by a corrected authorization or a new authorization, not by an appeal of the original denial.
- Does the documentation support medical necessity. The plan needs clinical notes showing symptoms, prior treatments tried, test results, and why this service, rather than a lower cost alternative, is needed now. A short letter that repeats the diagnosis without that reasoning rarely succeeds.
- What is the deadline and the channel. Note the appeal deadline from the denial letter, usually counted from the date on the letter or EOB, and use the channel the plan specifies for this denial type. A corrected claim, a peer to peer review, and a formal appeal are different processes with different forms and deadlines. Using the wrong one can miss the window.
Building an appeal that a reviewer can approve
A strong appeal packet has a clear structure. Start with a one paragraph summary: who you are, what service was denied, when it was provided or requested, and what you are asking for. Then attach, in order, the denial letter, the EOB, the authorization request and approval if any, the clinical notes, relevant test results, and any guidelines or prior treatment records that support necessity.
The clinician letter should answer the reviewer questions directly. What is the diagnosis and how was it confirmed. What symptoms or functional limits does the patient have. What treatments have already been tried, and what happened. Why is this service needed now, and why is a lower cost alternative not suitable for this patient. What happens if the service is delayed. Vague statements such as the patient needs this test should be replaced with specific clinical facts from the notes, because reviewers decide on facts, not on urgency alone.
If the plan offers a peer to peer review, where the treating clinician speaks directly with a plan clinician, use it when available. Many authorization denials are overturned in that conversation, because the plan clinician can ask follow up questions that a paper packet cannot answer. Ask the treating clinician office to request it promptly, because peer to peer windows are often short.
Common mistakes, and how to avoid them
Appealing the wrong denial is the most common mistake. A denial for missing authorization, a denial for coding, and a denial for not covered service need different fixes, and an appeal that argues medical necessity will not fix a missing authorization number. Read the denial reason code first, and ask the plan for a plain language explanation if the code is unclear.
A second mistake is resubmitting the same claim without change. A resubmission with the same missing authorization, same code, and same documentation will usually be denied again, and may be flagged as a duplicate. Fix the cause, then resubmit or appeal through the correct channel.
A third mistake is missing the deadline while gathering records. Note the deadline on the day the denial arrives, start the records request the same week, and submit what you have by the deadline with a note that additional records will follow if the plan allows supplements. A late appeal is often denied on timing alone, regardless of merit.
What patients can do, and what providers usually handle
Patients can check the denial reason, note deadlines, gather their own records, and ask both the provider office and the plan who is handling the appeal and by when. Providers usually handle the clinical documentation, the authorization request, and the peer to peer review, because those steps need clinical notes and coding knowledge. If the provider office says it will appeal, ask for the submission date and reference number in writing, and follow up before the deadline if you hear nothing.
If a first appeal is denied, check whether a second level appeal, an external review, or a state complaint process applies. HealthCare.gov and your state insurance department explain external review rights for many plans, and the denial letter should state which levels are available to you. Keep every response in writing, because each level builds on the previous record.
What a complete request packet contains
A complete packet answers the reviewer questions before they are asked. It contains the patient and provider identification, the exact service requested, the diagnosis and how it was confirmed, the symptoms and functional limits, the treatments already tried and their outcomes, the relevant test results, and the reason a lower cost alternative is not suitable for this patient, where that question applies. It also contains the authorization form or reference, the dates requested, and the provider and facility details. Missing any one of those pieces can trigger a request for more information, which resets the clock and delays care.
The clinician letter is the heart of the packet, and it works best when it is specific. A letter that lists dates of prior treatments, doses or durations where relevant, response to each treatment, and current symptoms with impact on daily life gives a reviewer facts to approve. A letter that repeats the diagnosis and states that the service is needed, without that history, leaves the reviewer to guess.
If you write a patient statement to attach, describe symptoms in your own words, how they affect work, sleep, walking, or daily tasks, what you have already tried, and what happened. Patient statements do not replace clinical notes, but they add the functional picture that notes sometimes miss.
Keep a copy of the whole packet, with the submission date and reference number, because appeals build on the original packet. If the plan later says a document was missing, your copy proves what was sent and when. If the service changes after submission, tell the provider office promptly, because an approval for one service does not automatically cover a changed service, and a new or amended request may be needed before the new service date.
When the approval does not match the service that happens
Approvals are specific, and real care often changes. A different imaging study, a different provider covering the clinic that day, a different facility, or a date outside the approval window can all break the match, even when the clinical need is unchanged. Before the service date, compare the approval letter with the appointment details: service, provider, facility, diagnosis, and dates. If any detail differs, ask the provider office whether an amended approval is needed, and do not assume the difference is minor. A small administrative difference can become a full denial after the service, when correction is much harder.
If the service must change on the day, for clinical reasons, ask the treating team to document why the change was needed, what was done instead, and how it relates to the original request. That documentation supports a later correction or appeal, where the plan allows it. If the service is rescheduled, check that the new date still falls inside the approval window, and ask for an extension before the window expires, rather than after the service. Extensions are far easier to obtain before expiry than retroactive approvals after expiry.
Also check what happens after approval but before payment. Eligibility on the date of service, correct coding, and complete documentation still matter. An approved service billed with the wrong code, or for a patient whose coverage ended before the service date, can still be denied for those separate reasons. That is why the article stresses that authorization is not a payment promise: it is one gate, not the whole payment decision.
Preparing for a peer to peer review
A peer to peer review is a conversation between the treating clinician and a plan clinician, and preparation decides whether it helps. The treating clinician should have the notes, test results, prior treatment history, and the denial reason in front of them, plus a short summary of why this service, for this patient, now, rather than an alternative. The patient can help by providing a clear symptom history, a list of prior treatments and outcomes, and a note of how symptoms affect daily life, before the call, so the clinician does not have to reconstruct the history from memory.
During the call, the plan clinician may ask about alternatives, about test results, or about timing. Specific answers help more than general urgency. After the call, ask the treating office for the outcome in writing: approved, denied, or pending more information, with a reference number and the date. If the outcome is approval, confirm the approved service, provider, facility, and dates, and check them against the appointment before the service happens. If the outcome is denial, ask what the next level is, and what the deadline is, because peer to peer windows and appeal windows are separate clocks.
Second level appeals, external review, and keeping the record straight
If a first appeal is denied, read the new denial letter as carefully as the first. It may give a different reason, cite a different guideline, or offer a different level of review. A second level appeal usually needs new information or a stronger clinical argument, not a repeat of the first packet. Ask what new evidence would change the decision, and whether a different clinician letter, additional test results, or a guideline reference would help.
If the plan offers an external review, where an independent reviewer outside the plan decides, check eligibility, deadline, and the channel for that review, because external review is often the strongest patient protection for a medical necessity denial.
Keep a single timeline for the whole case: request date, approval or denial date, peer to peer date, appeal dates, and every response date, with reference numbers and copies of every letter. That timeline prevents missed deadlines, proves what was submitted when, and lets a new clinician, adviser, or reviewer pick up the case without starting over. When you call, quote the timeline dates and reference numbers, because they show the office and the plan that the case is tracked, and they speed up the search for your file.
Frequently asked questions
Does prior authorization guarantee payment?
No. Authorization means the plan agreed the service was medically necessary under its rules at the time of review. Payment still depends on eligibility on the date of service, correct coding, and plan coverage terms.
Can authorization be obtained after the service?
Sometimes, in limited circumstances such as urgent care or a plan error, but many plans deny retroactive requests. Ask the plan promptly, and ask the provider office whether the service can be rescheduled with authorization if retroactive approval is not available.
How long do I have to appeal?
It depends on the plan and the denial type, and the deadline is usually counted from the date on the denial letter or EOB. Read that letter promptly, note the deadline in writing, and do not wait for records to arrive before starting the appeal.
Who should write the appeal letter?
The treating clinician or the provider billing office usually writes the clinical appeal, because it needs notes and coding detail. You can write a patient statement describing symptoms, functional limits, and prior treatments in your own words, and attach it to the clinical packet.
Related reading on this site
For the full denial reasons and appeal steps, read Why Medical Claims Get Denied. For how to read the EOB that carries the denial reason, read How to Read an Explanation of Benefits.
