Denial Code 231 (CO-231, PR-231) — Meaning & What to Do
Claim Adjustment Reason Code (CARC)
What denial code 231 means: This service isn't paid separately when done on the same day as another.
What to do about denial code 231: A bundling rule — usually not a separate patient charge.
CO-231 vs PR-231 vs OA-231: what the prefix means
| Code on your EOB | What the prefix means | Who typically pays |
|---|---|---|
| CO-231 | Contractual obligation — the provider writes the amount off | Usually not the patient |
| PR-231 | Patient responsibility | The patient |
| OA-231 | Other adjustment | Often another payer or plan |
The prefix tells you who is expected to absorb the amount; the number (231) tells you why.
Seeing denial code 231 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 227Information requested from the patient wasn't received.
CARC 234This procedure isn't paid separately.
CARC 226The information requested from the provider wasn't received or was incomplete.
CARC 236This code combination isn't allowed together under coding rules.
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 231
What does denial code 231 mean on my EOB?
This service isn't paid separately when done on the same day as another.
What should I do about denial code 231?
A bundling rule — usually not a separate patient charge.
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.