On the CMS-1500 claim form, Box 23 holds the prior authorization number — the number the payer issued when it approved the billed services in advance. This guide explains what the box means and where Pabau takes the value from.
NOTE: This article is part of the US Insurance Billing Additional Resources series, which walks through every box of the CMS-1500. If you are new to claims in Pabau, start with Creating a US Professional (CMS 1500) Claim.
Box 23 — Prior authorization number
Some payers require services to be authorized before they are performed. When they do, they issue an authorization number, and Box 23 is where that number goes so the payer can match the claim to its approval. The box is situational: on a claim for services that needed no pre-authorization it simply stays empty. (The NUCC also allows a referral number or CLIA number in this cell for certain claim types; on Pabau claims the box carries the prior authorization number.)
How Pabau fills it
The value lives in the Claim details section of the claim, in the Prior authorization number field. You rarely type it there by hand: Pabau prefills it from the auth case attached to the appointment, and the field stays editable per claim, so you can correct or replace the number before validating and sending.
Auth cases live on the client card: open the Insurance tab of the left panel and scroll to CASE DETAILS, below the insurance policies. Each case carries the payer-issued authorization number for a course of treatment, and when you book the appointment you attach the case via the booking's Auth case option — that is what carries the number onto the claim.
On the electronic claim: the number is sent to Claim.MD as the prior authorization number, which lands in Loop 2300, Segment REF with qualifier G1.
TIP: When a payer issues an authorization, record it as an auth case on the client card and attach the case at booking — every claim from those appointments then carries the number without retyping. Box 23 is situational, so leave the field empty when no authorization was required.
To set up auth cases and link appointments to insurance, see Insurance Guide Part 3: Connect Appointments to Insurance in Pabau.