Claim adjustment reason code
Denial code CO-B10 meaning
CARC B10, usually seen as CO-B10: The allowed amount was cut because a component of the procedure or test was already paid.
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- Reason code
- CARC B10
- Short name
- Reduced because a component was paid
- Plain meaning
- The allowed amount was cut because a component of the procedure or test was already paid.
- Group codes
- CO-B10: Contractual obligation. The provider absorbs the amount under its contract or the payer's rules. Do not bill the patient for it.
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 professional or technical component was billed and paid separately.
What to check before resubmitting
- Check the 26 and TC modifiers on both claims.
Related reason codes
Related pages
Questions
What does denial code CO-B10 mean?
The allowed amount was cut because a component of the procedure or test was already paid. This is Rivvi's plain-English summary of CARC B10. X12's exact wording is on x12.org.
How do I fix CO-B10?
Check the 26 and TC modifiers on both claims.
Can I bill the patient for CO-B10?
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 B10?
Most often CO (contractual obligation). 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.