Exact duplicate claim
The payer already has a claim with the same patient, provider, date, code and charge. This one was treated as a repeat.
OA = Other Adjustment. Neither the provider nor the patient is being told to pay. Used when no other group fits, for example when another payer should pay. The same reason code can appear with a different group code; the group decides who may be billed.
Usual causes
- The claim was sent twice (resubmitted before the first one finished).
- Two services on the same day that look identical and needed a modifier (76, 77, 59 or 91) to show they were separate.
- A corrected claim sent as a new claim (frequency code 1) instead of a replacement (frequency code 7).
The fix
Check the status of the first claim. If it paid, nothing to do. If a second distinct service was done, add the right modifier and resubmit. If you meant to correct the first claim, resend it as a corrected claim with the original claim number.
Appeal or corrected claim?
Usually nothing to appeal. Resubmit with the modifier or as a corrected claim when the second service was real.
Deadline to watch
Timely filing limit from the date of service.
Exact limits are in your payer contract or provider manual. When in doubt, send the correction or appeal this week.
Often seen together
Your secondary claim duplicated the automatic Medicare crossover. Nothing to send unless the primary remittance shows the crossover failed.
OA-18 in short
What does OA-18 mean?
The payer already has a claim with the same patient, provider, date, code and charge. This one was treated as a repeat. The official X12 text reads: "Exact duplicate claim/service (Use only with Group Code OA except where state workers' compensation regulations requires CO)"
What usually causes a OA-18 denial?
The claim was sent twice (resubmitted before the first one finished). Two services on the same day that look identical and needed a modifier (76, 77, 59 or 91) to show they were separate. A corrected claim sent as a new claim (frequency code 1) instead of a replacement (frequency code 7).
How do I fix OA-18?
Check the status of the first claim. If it paid, nothing to do. If a second distinct service was done, add the right modifier and resubmit. If you meant to correct the first claim, resend it as a corrected claim with the original claim number.
Should I appeal OA-18 or send a corrected claim?
Nothing to send. Usually nothing to appeal. Resubmit with the modifier or as a corrected claim when the second service was real.
What deadline applies to OA-18?
Timely filing limit from the date of service.