A single physician’s practice completes 39 prior authorization requests in a typical week. Staff spend about 13 hours getting through them. Those figures come from a 2024 survey of 1,000 physicians conducted by the American Medical Association, and they explain why prior authorization in medical billing has become one of the most closely watched steps in the revenue cycle. Approval sits between the clinical decision and payment. Handle it well and claims move. Handle it poorly and the practice absorbs denials, delayed care, and hours of unpaid administrative work.
This guide explains what prior authorization is, the different types you may encounter, how the process works, how long approvals remain valid, and the federal and state regulations shaping prior authorization in 2026.
What is prior authorization in medical billing?
Prior authorization is the approval a provider must obtain from a patient’s health plan before delivering a service, procedure, or medication, so the plan agrees to cover it. You will see the same step written as pre-authorization, preauthorization, or shortened to prior auth or PA. Payers use these labels interchangeably, and so do most billing teams.
Not every service needs it. Plans publish lists of procedures, drugs, and equipment that require approval, and those lists change. High-cost imaging (MRI and CT scans), elective surgery, specialty medications, durable medical equipment, and inpatient admissions are common triggers.
When a plan approves a request, it issues an authorization number. That number connects the approved service to the claim submitted later for payment. Billers enter it on the claim so the payer’s system can match the approval to the charge. Omit it, or transpose a digit, and the claim can be rejected even though the care itself was authorized. The authorization number is also how staff confirm, weeks later, that an approval is still active.
Why payers require prior authorization
Health plans describe prior authorization as a check on cost and appropriateness. The stated purpose is to confirm that a requested service meets the plan’s medical necessity criteria before money changes hands, and to steer clinicians toward lower-cost options when the plan considers them equivalent. A plan might require a trial of physical therapy before approving an MRI for certain back pain, or a generic drug before covering a brand-name one.
Physicians see the same process differently. In the AMA’s 2025 prior authorization physician survey, released in May 2026, 93% of the 1,000 physicians polled said prior authorization can delay patient care, and 82% said it can lead patients to abandon a recommended treatment. More than a quarter (26%) reported that a prior authorization requirement had contributed to an adverse event for a patient. The distance between the cost-control rationale and the clinical experience is why the process draws so much regulatory attention.
Types of authorization in medical billing
Authorization is not a single event. It can happen at different points relative to the care itself, and the timing changes what the request is called and what documentation it needs.
Prior (prospective) authorization happens before the service. This is the standard case and what most people mean by the term.
Concurrent authorization happens while care is ongoing. A hospital seeking to extend an inpatient stay, or a therapist continuing treatment beyond an approved number of visits, files a concurrent request so coverage continues without a gap.
Retrospective (retro) authorization happens after the service has been delivered. It applies mainly to emergencies, or to situations where a patient’s coverage could not be confirmed in advance. Not every payer allows it, and the window to request it is short.
Precertification is often used as a synonym for prior authorization, though some payers reserve it for confirming that an admission or specific service is covered and medically necessary. Usage is inconsistent across plans, so billers confirm what a given payer means rather than assuming.
Type | When it happens | Typical use |
Prior / prospective | Before the service | Elective procedures, imaging, specialty drugs |
Concurrent | During ongoing care | Extending an inpatient stay or therapy course |
Retrospective (retro) | After the service | Emergencies, coverage unverifiable at time of care |
Precertification | Before or at admission | Confirming coverage and necessity, often inpatient |
How the prior authorization process works
The workflow varies by payer, but the sequence is consistent.
- Verify eligibility and requirements. Before anything else, staff confirm the patient’s active coverage and check whether the specific service needs authorization under that plan. Requirements differ by payer and can differ between plans from the same insurer.
- Assemble clinical documentation. The request has to show medical necessity. That means the correct diagnosis (ICD-10) and procedure (CPT) codes, plus supporting records: physician notes, test results, prior treatments attempted, and any imaging.
- Submit the request. Depending on the payer, submission happens through an online portal, a payer’s electronic prior authorization system, fax, or phone. Complete, accurate submissions move faster.
- Payer review. The plan measures the request against its clinical criteria. Straightforward cases may clear quickly. Others route to a medical reviewer.
- Peer-to-peer review, if needed. When a plan is inclined to deny, the ordering physician can request a peer-to-peer review, a direct conversation with a plan reviewer to argue the clinical case. Physicians frequently criticize these calls: in the 2025 AMA survey, only 16% of physicians who take part in peer-to-peer reviews said the plan’s representative usually had the right clinical qualifications.
- Decision. An approval comes with an authorization number and, usually, an effective date range. A denial comes with a reason, which the practice can use to correct and resubmit, or to file an appeal.
How long a prior authorization stays valid
An approval is not open-ended. Most authorizations carry an expiration date, and the window depends on the payer and the service. Many run 30 to 90 days from the date of approval, but some are shorter, some cover a set number of visits, and some extend across a longer treatment period. A surgery approved today may need to occur within a defined window, or the practice has to start over.
Two developments have loosened this in specific settings. Under state gold card laws and recent Medicare Advantage changes, some payers now let approvals for ongoing, medically necessary treatment stay valid without repeated re-authorization. Even so, the safe practice is to record every authorization’s expiration date and confirm it is still active before the service is delivered, because a lapsed approval becomes a denied claim.
The shift from fax to electronic prior authorization
For years, prior authorization ran on phone calls and fax machines. That is changing, slowly. According to the 2024 CAQH Index, only 35% of medical prior authorizations were conducted fully electronically through the standard X12 278 transaction. The 2025 CAQH Index put electronic adoption at 40%, still the lowest among the major administrative transactions it tracks. CAQH estimates that moving the remaining manual administrative work to electronic formats could save the U.S. medical and dental industries more than $20 billion a year.
Electronic prior authorization (ePA) lets a practice submit requests and supporting documentation through connected systems rather than faxing paperwork and waiting on hold. Adoption has lagged partly because of the transaction’s technical limits and the difficulty of attaching clinical documentation, which is exactly what the newest federal rules aim to fix.
What changed in 2024, 2025, and 2026
Two developments are reshaping the process now.
The first is a federal rule. On January 17, 2024, the Centers for Medicare and Medicaid Services released the Interoperability and Prior Authorization Final Rule (CMS-0057-F). It applies to Medicare Advantage plans, state Medicaid and CHIP managed care programs, and qualified health plans sold on the federally facilitated exchanges. As of January 1, 2026, those payers must decide expedited requests within 72 hours and standard requests within seven calendar days, and they must give a specific reason for every denial. By January 1, 2027, they must build standardized HL7 FHIR application programming interfaces, including a dedicated Prior Authorization API, and begin publicly reporting metrics such as approval and denial rates.
The second is voluntary. In June 2025, after engagement from the Trump administration, roughly 60 health insurers pledged to simplify prior authorization, with commitments rolling out between 2025 and 2027. Physicians are skeptical. In the AMA’s 2025 survey, only 33% expected the pledge to make a meaningful difference, a reaction shaped by a similar 2018 industry consensus statement that produced little lasting change.
At the state level, gold carding takes a different route. Texas passed the first such law (HB 3459) in 2021, exempting physicians who reach a 90% approval rate over six months from future authorization for those services. At least 10 states have since required gold card programs. Results have been modest: the Texas Department of Insurance reported that only about 3% of physicians in the state qualified under the original threshold.
Common reasons a prior authorization gets denied
Most denials trace back to a handful of avoidable problems:
- Incomplete or missing clinical documentation to support medical necessity
- Diagnosis and procedure codes that do not match, or that do not justify the requested service
- A service the plan does not cover, or that fails the plan’s necessity criteria
- Coverage that lapsed or changed before the service date
- A request submitted after the service when the payer does not allow retrospective authorization
- The request sent to the wrong plan, portal, or form
A denial is not always final. When the underlying issue is documentation or coding, correcting the record and resubmitting often resolves it. When the dispute is over medical necessity, the appeal and peer-to-peer routes exist for that reason.
Practical steps for a faster workflow
Practices that keep denials low tend to share a few habits.
- Check eligibility and authorization requirements before scheduling, not after.
- Keep a current, payer-specific list of which services need approval, since the lists change.
- Submit complete documentation the first time rather than responding to repeated requests for more.
- Use electronic portals and ePA where the payer offers them, and reserve fax for payers that still require it.
- Log every authorization number and expiration date, and check the date before the service.
- Prepare the ordering physician for a possible peer-to-peer review, including relevant records and availability.
- Track denials by payer and reason to catch patterns worth fixing at the source.
None of these steps is complicated on its own. The difficulty is doing them consistently across dozens of payers, which is why staffing this work reliably is a genuine challenge for many practices.
Where prior authorization services fit
Because the work is repetitive and time-consuming, many practices assign it to a dedicated team, either in-house or through a billing partner. The AMA’s 2024 survey found that 40% of physicians employ staff who work exclusively on prior authorization. Outsourced prior authorization services handle eligibility checks, requirement lookups, documentation, submission, status follow-up, and appeals, and they track authorization numbers and expiration dates so approvals do not lapse.
A2Z Billings provides prior authorization support as part of its medical billing services, managing the submission and follow-up process so clinical staff spend less time on payer paperwork. Whether a practice keeps the work internal or outsources it, the aim is the same: fewer denials, faster approvals, and clinical staff freed to focus on patients rather than forms.
The direction of travel is clear enough. Federal turnaround limits took effect in 2026, standardized electronic interfaces are due in 2027, and payers are under public pressure to show their voluntary commitments amount to more than words. For prior authorization in medical billing, the practical takeaway has not changed: accurate documentation, careful tracking, and early verification remain the difference between an approved claim and an unpaid one, no matter how much the rules around them shift.