Claim adjustment reason code
Denial code CO-6 meaning
CARC 6, usually seen as CO-6: The procedure or revenue code is not expected for a patient of this age.
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- Reason code
- CARC 6
- Short name
- Code does not fit the patient's age
- Plain meaning
- The procedure or revenue code is not expected for a patient of this age.
- Group codes
- CO-6: 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 date of birth on the claim is wrong.
- An age-specific code, such as a pediatric or preventive code, was billed for the wrong age band.
What to check before resubmitting
- Check the date of birth against the patient's ID card.
- Choose the code for the patient's actual age.
Related reason codes
Related pages
Questions
What does denial code CO-6 mean?
The procedure or revenue code is not expected for a patient of this age. This is Rivvi's plain-English summary of CARC 6. X12's exact wording is on x12.org.
How do I fix CO-6?
Check the date of birth against the patient's ID card. Choose the code for the patient's actual age.
Can I bill the patient for CO-6?
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 6?
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.