Denial Code 1 (CO-1, PR-1) — Meaning & What to Do
Claim Adjustment Reason Code (CARC)
What denial code 1 means: This amount is your deductible — the part you pay before insurance starts covering costs.
What to do about denial code 1: This is usually a legitimate patient cost. Confirm the amount matches your plan's deductible.
CO-1 vs PR-1 vs OA-1: what the prefix means
| Code on your EOB | What the prefix means | Who typically pays |
|---|---|---|
| CO-1 | Contractual obligation — the provider writes the amount off | Usually not the patient |
| PR-1 | Patient responsibility | The patient |
| OA-1 | Other adjustment | Often another payer or plan |
The prefix tells you who is expected to absorb the amount; the number (1) tells you why.
Seeing denial code 1 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 2This amount is your coinsurance — your percentage share of the cost.
CARC 3This amount is your copay — a fixed fee for the visit or service.
CARC 4The procedure code doesn't match a required modifier, or the modifier is missing/invalid.
CARC 16The claim is missing information or has an error that must be fixed before it can be processed.
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 1
What does denial code 1 mean on my EOB?
This amount is your deductible — the part you pay before insurance starts covering costs.
What should I do about denial code 1?
This is usually a legitimate patient cost. Confirm the amount matches your plan's deductible.
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.