Denial Code 11 (CO-11, PR-11) — Meaning & What to Do
Claim Adjustment Reason Code (CARC)
What denial code 11 means: The diagnosis doesn't match the procedure that was billed.
What to do about denial code 11: Ask the provider's billing office to explain or correct this, and resubmit if needed.
CO-11 vs PR-11 vs OA-11: what the prefix means
| Code on your EOB | What the prefix means | Who typically pays |
|---|---|---|
| CO-11 | Contractual obligation — the provider writes the amount off | Usually not the patient |
| PR-11 | Patient responsibility | The patient |
| OA-11 | Other adjustment | Often another payer or plan |
The prefix tells you who is expected to absorb the amount; the number (11) tells you why.
Seeing denial code 11 on your EOB?
A denial code tells you what the payer reported, but it may not tell the whole story. Reviewing your EOB and bill together can help clarify what may need attention.
Related codes
CARC 9The diagnosis doesn't match the patient's age.
CARC 13The date of service is after the patient's date of death on record.
CARC 8The procedure code doesn't match the provider's specialty.
CARC 15The authorization number is missing, invalid, or doesn't apply to this service.
Keep reviewing your bill
- Medical Bill vs EOB: What Is the Difference?
- How to Dispute a Medical Bill — Find Billing Errors Before You Pay
- What Is an Itemized Medical Bill? How to Request One
Frequently asked questions about Denial code 11
What does denial code 11 mean on my EOB?
The diagnosis doesn't match the procedure that was billed.
What should I do about denial code 11?
Ask the provider's billing office to explain or correct this, and resubmit if needed.
Seeing this code on your own EOB?
Upload the EOB, the bill, or both — MD Bill Check reads the codes on your documents, compares them side by side, and flags what's worth questioning. Free, no account needed.