Denial Code 110 (CO-110, PR-110) — Meaning & What to Do
Claim Adjustment Reason Code (CARC)
What denial code 110 means: The billing date comes before the service date.
What to do about denial code 110: A data error — ask the provider to correct the dates.
CO-110 vs PR-110 vs OA-110: what the prefix means
| Code on your EOB | What the prefix means | Who typically pays |
|---|---|---|
| CO-110 | Contractual obligation — the provider writes the amount off | Usually not the patient |
| PR-110 | Patient responsibility | The patient |
| OA-110 | Other adjustment | Often another payer or plan |
The prefix tells you who is expected to absorb the amount; the number (110) tells you why.
Seeing denial code 110 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 108Adjusted under a rental/purchase rule for equipment.
CARC 111This provider isn't certified or eligible to be paid for this service.
CARC 107A related service or claim is required but wasn't found.
CARC 114This procedure or service isn't covered when done at home.
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 110
What does denial code 110 mean on my EOB?
The billing date comes before the service date.
What should I do about denial code 110?
A data error — ask the provider to correct the dates.
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.