What services require prior authorization?

It varies by payer and plan, but services that commonly require prior authorization include advanced imaging like MRI and CT scans, certain surgeries and procedures, expensive or specialty medications, durable medical equipment, and some specialist services. The first step is always checking whether a specific service requires it for the patient's plan.

Why do claims get denied for missing prior authorization?

If a service that required prior authorization is provided without obtaining it, the payer usually denies the claim, and that denial is often difficult to overturn. The payer's position is that approval was required in advance and wasn't secured, so the service may not be paid at all.

Can a missing prior authorization be fixed after the service?

Sometimes, but often not. Some payers allow retroactive or expedited authorization in limited circumstances, but many do not, which is why a missing prior auth is one of the harder denials to recover. The reliable approach is to check for and obtain authorization before the service is provided.

Insights

What Is Prior Authorization? Why Claims Get Denied Without It

September 7, 2026AlphaTek Solutions

Prior Authorization
Medical Billing
Healthcare

Some of the most frustrating denials in medical billing aren't coding mistakes — they're claims for services that were provided without getting approval first. That approval is called prior authorization, and missing it is one of the most common (and most preventable) reasons a claim gets denied. Here's what it is and how to stay ahead of it.

What is prior authorization?

Prior authorization (also called pre-authorization or pre-certification) is approval a healthcare provider must get from the insurance payer before providing certain services, medications, or equipment. It's the payer confirming, in advance, that it considers the service covered and medically necessary.

The key word is before. Prior auth isn't something you sort out after the fact — it has to be obtained before the service is delivered, or the payer may refuse to pay for it.

Why it exists

Payers use prior authorization to control costs and confirm medical necessity. For certain higher-cost or higher-scrutiny services, they want to review the request before agreeing to pay, rather than after. Whether or not providers love it, it's a standard part of how many payers operate — so working with it is part of the billing job.

What typically needs prior authorization

It varies by payer and plan, but services that commonly require it include:

Advanced imaging — MRI, CT, PET scans
Certain surgeries and procedures
Some medications — especially expensive or specialty drugs
Durable medical equipment (DME)
Certain specialist referrals or services

Because the rules differ by payer, the first step is always checking whether a specific service requires authorization for that specific patient's plan.

Why claims get denied without it

Here's the painful part: if a service that required prior authorization is provided without obtaining it, the claim is usually denied — and that denial is often difficult or impossible to overturn. The payer's position is straightforward: the service needed approval in advance, and it wasn't obtained.

Unlike some denials that can be corrected and resubmitted, a missing-prior-auth denial can mean the service simply won't be paid. That makes it one of the more costly denial types, and one worth preventing every time.

How the prior authorization process works

The basic flow:

Check whether the service requires prior authorization for the patient's plan.
Submit the request to the payer with supporting clinical documentation showing medical necessity.
Wait for the payer's decision (approval, denial, or a request for more information).
Proceed only once approval is in hand — then provide the service and bill it.

The discipline is in step 1: catching that a service needs authorization before it's scheduled, not after it's already been done.

Why it matters

Missing prior authorizations are a leading, preventable cause of lost revenue. The service was delivered, the cost was incurred — but because approval wasn't obtained first, the payment never comes. Building a reliable process to check and secure authorizations up front is one of the highest-return things a practice can do to protect its revenue.

Where AlphaTek fits

At AlphaTek Solutions, managing prior authorizations and preventing the denials they cause is part of our medical billing and denial management work — checking requirements, securing approvals, and documenting medical necessity before services are billed. If auth-related denials are costing you, talk to us.

Frequently asked questions

What is prior authorization?: Prior authorization is approval a provider must get from an insurance payer before providing certain services, medications, or equipment. It confirms in advance that the payer considers the service covered and medically necessary. It must be obtained before the service is delivered, not after.
What services require prior authorization?: It varies by payer and plan, but services that commonly require prior authorization include advanced imaging like MRI and CT scans, certain surgeries and procedures, expensive or specialty medications, durable medical equipment, and some specialist services. The first step is always checking whether a specific service requires it for the patient's plan.
Why do claims get denied for missing prior authorization?: If a service that required prior authorization is provided without obtaining it, the payer usually denies the claim, and that denial is often difficult to overturn. The payer's position is that approval was required in advance and wasn't secured, so the service may not be paid at all.
Can a missing prior authorization be fixed after the service?: Sometimes, but often not. Some payers allow retroactive or expedited authorization in limited circumstances, but many do not, which is why a missing prior auth is one of the harder denials to recover. The reliable approach is to check for and obtain authorization before the service is provided.

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