What is denial code CO-11?
CO-11 means the payer found the diagnosis on the claim doesn't support the procedure billed, for example a knee diagnosis on a shoulder procedure.
Remittance advice, claim line
- Diagnosis billed
- M25.561 Pain in right knee
- Note says
- Right shoulder pain after a fall, limited abduction
| Service | Billed | Paid | Adjustment |
|---|---|---|---|
| 73030 X-ray shoulder, 2 views | $96.00 | $0.00 | CO-11 $96.00 |
- The note documents shoulder pain, M25.511. A corrected claim with the documented diagnosis fixes it.
Reason code 11 reads: The diagnosis is inconsistent with the procedure. Payers run edits that pair procedure codes with the diagnoses that can justify them, and this denial means the pair failed.
Common causes
- A wrong or mistyped diagnosis code.
- The right diagnosis exists in the record but wasn’t put on the claim, or wasn’t pointed to from the service line.
- A diagnosis that is too general for the payer’s edit.
How to resolve it
Read the note. If it documents a diagnosis that supports the service, send a corrected claim with that code; coding changes need a coder’s review. If the billed diagnosis was right and the payer’s edit is the problem, treat it as a medical necessity appeal instead. Never add a diagnosis the record doesn’t support.
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