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CARC
CO-18
CARC
CO — Contractual Obligation
Duplicate/Timely Filing
Quick Facts
Code
CO-18
Type
CARC
Category
Duplicate/Timely Filing
Status
Active
Duplicate claim or service
What Does This Code Mean?
The payer’s system identified this claim or service line as a duplicate of one already submitted and processed.
Common Causes
- Claim resubmitted before the original finished processing
- Same service billed by two different staff members
- Clearinghouse submitted the batch twice
- Corrected claim submitted without the required frequency code
Recommended Next Steps
- Pull the original claim's status before resubmitting anything
- If it truly is a duplicate, no action needed — do not resubmit
- If it's a correction, use frequency code 7 (replacement) or 8 (void) on the 837
- Call the payer if the original claim shows no record on their end
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Educational reference only — not medical or legal advice. Always confirm code usage and appeal rights with the specific payer.