CO-11 denial code
The diagnosis does not match the procedure. The payer is saying the reason you gave for the service does not justify the service you performed.
CO — Contractual Obligation. The write-off is yours. You agreed to it in your contract with the payer, and you cannot bill the patient for it.
Why you got it
- 1The diagnosis submitted genuinely does not support the procedure.
- 2The right diagnosis is in the chart but a different one was linked to the line item.
- 3The diagnosis pointer on the claim line points at the wrong diagnosis.
- 4An unspecified code was used where a specific one would have supported the service.
How do I fix a CO-11 denial?
- Check the diagnosis pointers first. A correct diagnosis linked to the wrong line is one of the most common versions of this, and it is a clerical fix.
- Re-read the documentation for a diagnosis that supports the service. If one exists and was simply not coded, recode and resubmit.
How to stop the next one
Most of these are a mismatch the coder could have seen. The rest are coverage-policy problems, which are also knowable in advance.
We can catch the coding cause of this one before you submit
Paste the diagnosis codes into our free scrubber and it will flag the invalid, incomplete, and conflicting codes that produce CO-11 — quoting the CMS note behind each one. No signup.
Check a claim, freeIf denials like this are a volume problem rather than a one-off, the denial management page explains how the paid workspace catches the coding causes on every claim, and the free ICD-10-CM lookup shows the coding notes behind any diagnosis code on the remittance.