Denial Code 77 (CO-77, PR-77) — Meaning & What to Do
Claim Adjustment Reason Code (CARC)
What denial code 77 means: This is a covered service, but the charge is the patient's responsibility.
What to do about denial code 77: Confirm this matches your plan's cost-sharing before paying.
CO-77 vs PR-77 vs OA-77: what the prefix means
| Code on your EOB | What the prefix means | Who typically pays |
|---|---|---|
| CO-77 | Contractual obligation — the provider writes the amount off | Usually not the patient |
| PR-77 | Patient responsibility | The patient |
| OA-77 | Other adjustment | Often another payer or plan |
The prefix tells you who is expected to absorb the amount; the number (77) tells you why.
Seeing denial code 77 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 76Payment was already made for this service under another claim.
CARC 94Payment made was more than the charge, creating a credit.
CARC 59Charges were adjusted based on multiple or concurrent procedure rules.
CARC 95The provider billed in a way that doesn't follow the plan's 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 77
What does denial code 77 mean on my EOB?
This is a covered service, but the charge is the patient's responsibility.
What should I do about denial code 77?
Confirm this matches your plan's cost-sharing before paying.
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.