Claim adjustment reason code
Denial code CO-B13 meaning
CARC B13, usually seen as CO-B13: Payment for this claim or service may already have been made.
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- Reason code
- CARC B13
- Short name
- Previously paid
- Plain meaning
- Payment for this claim or service may already have been made.
- Group codes
- CO-B13: Contractual obligation. The provider absorbs the amount under its contract or the payer's rules. Do not bill the patient for it. OA-B13: Other adjustment. An adjustment that is neither the provider's nor the patient's, often from coordination of benefits.
Plain-English summary written by Rivvi. X12 owns the CARC list and its exact wording, which is not reproduced here. Read it on the X12 CARC list (list dated November 1, 2025, checked October 23, 2026). This page does not decide how a claim is paid.
Common causes
- The payer already paid the same service on another claim.
What to check before resubmitting
- Check earlier remittances before resending.
- If it was not paid, ask the payer which claim it matched.
Related reason codes
Related pages
Questions
What does denial code CO-B13 mean?
Payment for this claim or service may already have been made. This is Rivvi's plain-English summary of CARC B13. X12's exact wording is on x12.org.
How do I fix CO-B13?
Check earlier remittances before resending. If it was not paid, ask the payer which claim it matched.
Can I bill the patient for CO-B13?
With group code CO, no. CO means the provider absorbs the amount under its contract or the payer's rules.
Which group codes come with CARC B13?
Most often CO (contractual obligation) or OA (other adjustment). The group code, not the reason code, says who owes the amount.
What is the difference between a CARC and a RARC?
A claim adjustment reason code (CARC) says why a claim line was paid differently than billed. A remittance advice remark code (RARC) adds detail, such as which field is missing.