Claim adjustment reason code
Denial code CO-11 meaning
CARC 11, usually seen as CO-11: The payer does not see the diagnosis on the claim as a reason for the procedure billed.
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- Reason code
- CARC 11
- Short name
- Diagnosis does not support the procedure
- Plain meaning
- The payer does not see the diagnosis on the claim as a reason for the procedure billed.
- Group codes
- CO-11: 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 diagnosis is not on the payer's list of covered diagnoses for the code.
- The diagnosis pointer on the claim line points to the wrong diagnosis.
- A less specific diagnosis was billed.
What to check before resubmitting
- Check the diagnosis pointer on each line.
- Check the payer's coverage policy, and for Medicare the LCD or NCD, for covered diagnoses.
- Code to the highest specificity the documentation supports.
Remark codes that often come with it
Related reason codes
Related pages
Questions
What does denial code CO-11 mean?
The payer does not see the diagnosis on the claim as a reason for the procedure billed. This is Rivvi's plain-English summary of CARC 11. X12's exact wording is on x12.org.
How do I fix CO-11?
Check the diagnosis pointer on each line. Check the payer's coverage policy, and for Medicare the LCD or NCD, for covered diagnoses. Code to the highest specificity the documentation supports.
Can I bill the patient for CO-11?
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 11?
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.