Claim adjustment reason code
Denial code CO-10 meaning
CARC 10, usually seen as CO-10: The diagnosis code does not match the sex recorded for the patient.
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- Reason code
- CARC 10
- Short name
- Diagnosis does not fit the patient's sex
- Plain meaning
- The diagnosis code does not match the sex recorded for the patient.
- Group codes
- CO-10: 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
- A sex-specific diagnosis code does not match the payer's member record.
What to check before resubmitting
- Compare the claim to the payer's member record and the documentation.
Remark codes that often come with it
Related reason codes
Related pages
Questions
What does denial code CO-10 mean?
The diagnosis code does not match the sex recorded for the patient. This is Rivvi's plain-English summary of CARC 10. X12's exact wording is on x12.org.
How do I fix CO-10?
Compare the claim to the payer's member record and the documentation.
Can I bill the patient for CO-10?
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 10?
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.