# What is prior authorization?

Source: https://priorauth.getgenko.com/guides/what-is-prior-authorization · Updated 2026-10-18

Prior authorization (also called pre-authorization or pre-certification) is a health plan's decision, made before a service is delivered, about whether the service meets its criteria for coverage. The practice asks, the payer reviews, and treatment usually waits for the answer. This guide explains the moving parts in plain terms.

## The short definition

A payer (an insurer or a plan administrator) can require that certain services be approved before they happen. For those services the practice submits a request describing the patient, the planned service, the diagnosis and the clinical reasons the service is needed. The payer reviews it against its own medical-necessity criteria and answers: approved, partly approved, denied, or a request for more information.

> Which services need prior authorization, what a request must contain and how long a review takes differ by payer, plan and state. Always check the payer's current requirements; this guide describes the general pattern, not any one payer's rules.

## Who does what

| Who | What they do |
| --- | --- |
| The practice | Decides a service is needed, gathers clinical documentation, writes and submits the request, tracks it, and appeals if it is denied. |
| The payer | Sets the rules for which services need approval, reviews the request against its criteria, and issues a decision with a reason if it is not a full approval. |
| The patient | Is affected by delays and denials, and usually has appeal rights of their own. Practices often keep the patient informed while a request is pending. |

## Why payers require it

- To check that a service meets the plan's clinical criteria before paying for it.
- To steer toward a less costly alternative when the plan considers one equivalent.
- To confirm the patient is eligible and the service is covered under their plan.

## Why it is expensive for small practices

Each request is a small writing project: the clinical story has to be turned into the language a reviewer expects, the right codes have to match the narrative, and the supporting documents have to be attached. Requirements vary by payer, so experience with one payer does not transfer cleanly to the next. A missing document or a vague justification is a common reason for a request to come back, and that costs another round.

## An approval is not a guarantee of payment

Authorization generally means the service was found to meet medical-necessity criteria at the time of review. Payment can still depend on the patient's eligibility on the date of service, benefit limits and the service being delivered as described. Read the approval for its scope: the codes, dates and number of visits or units it covers.

## What to read next

- [What goes in a prior authorization packet](https://priorauth.getgenko.com/guides/prior-authorization-packet-checklist): a checklist for the request itself.
- [Appealing a denial](https://priorauth.getgenko.com/guides/appealing-a-prior-authorization-denial): what to do when the answer is no.
- [How Genkō Prior Auth helps](https://priorauth.getgenko.com/docs/getting-started): drafting the packet for your team to review.

## Related

- [What goes in a prior authorization packet](https://priorauth.getgenko.com/guides/prior-authorization-packet-checklist)
- [Appealing a prior authorization denial](https://priorauth.getgenko.com/guides/appealing-a-prior-authorization-denial)
- [Prior authorization for dental practices](https://priorauth.getgenko.com/specialties/dental)