CARC 23: Impact of the prior payer’s payment or adjustment
This adjustment reflects what the primary payer already paid or adjusted.
Group code context
Usually sent on secondary claims with group code OA or CO.
Common causes
- Secondary claim processed after primary payment
Step-by-step fix
- Check the amount against the primary EOB
- Post the adjustment
- Bill any remaining balance as the secondary payer's rules allow
Appeal guidance
Appeal only if the secondary payer used the wrong primary amounts.
When not to appeal
Do not appeal a correct coordination adjustment.
Prevention checklist
- Attach the primary EOB to secondary claims
- Post primary payments before billing secondary
Related codes
CARC 22: May be covered by another payer (coordination of benefits)
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Source and review
Official source ↗Last checked: 2026-10-05
Reviewed by: PracticeVendors editorial team
Educational reference. Confirm payer instructions and applicable contracts before taking action.