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.
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
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.
Found this code on your bill or EOB?
Upload the document — MD Bill Check decodes every code, checks the math line by line, and explains what's worth questioning.