Box 23: Prior authorization number
By Dr. Daniel Turner, DC · Reviewed September 2, 2026
What goes in Box 23 of the CMS-1500?
The authorization or referral number a payer issued in advance, when the billed services required one. One number per claim.
What does Box 23 mean for chiropractic billing?
Plans that route chiropractic through benefit managers frequently authorize visits in blocks; the visits beyond the initial allowance need the auth number riding here. The authorization usually exists, and the denial usually means it never made the claim.
The mistakes that turn this box into denials
- ✗Auth obtained but never entered
- ✗An expired or exhausted auth number reused
- ✗Two different auths needed but only one claim number field
The denials this box causes
- →CO-197 · see the full fix in the denial library
How Cervica fills Box 23
Cervica generates the CMS-1500 and its electronic 837P equivalent from the chart and the payer's own rules: identifiers from the verified insurance record, modifiers and codes per payer, and pre submission scrubbing that flags exactly the mistakes listed above before a claim leaves the building.
Related boxes
- →Box 17, 17a, 17b · Referring provider and NPI
General information for billing teams, not billing advice for any individual claim. The NUCC's 1500 Claim Form instructions and each payer's companion guides control.