OA-18 — Exact duplicate claim
What it means
The payer already has this exact claim on file, so the second one was set aside. Not a real denial of the service — usually a double-submission.
Standard definition (paraphrased): The payer's system already has this identical claim on file from an earlier submission.
Why it happens
- • The claim was submitted twice (portal + clearinghouse, or a resend)
- • A corrected claim was sent without the correction indicator, so it read as a duplicate
Common next steps therapists take
- • Check whether the original claim was received and how it adjudicated
- • If a correction was intended, resubmit it flagged as a corrected claim, not a new one
Educational information only
This page is general educational information, not legal, billing, or medical advice, and not a determination about any specific claim. Denial codes are maintained by the X12 committee and updated periodically. Always verify code meanings, benefits, and requirements directly with the payer and against your own records.
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