CARC 18 denial code: meaning & whether to appeal (verified)
What CARC 18 means
Exact duplicate claim/service (Use only with Group Code OA except where state workers' compensation regulations requires CO)
Verbatim description from the official X12 Claim Adjustment Reason Codes list.
Classification
Routing category: duplicates
Appealability verdict
Verify duplicate status first
What to know
Confirm whether the claim is a true duplicate before responding. If the payer's duplicate flag is wrong, respond with proof of the distinct service or of the original timely submission.