RARC MA18: Claim Information Forwarded to the Patient's Supplemental Insurer
RARC MA18 is an alert telling you the claim was automatically forwarded (crossed over) to the patient's supplemental insurer — Medicare sent it to the Medigap or secondary plan for you. It is not a denial. The action is to wait for the crossover to pay and not bill the secondary manually, which would create a duplicate.
- Type
- Informational (Alert)
- Usually paired with
- Paid/adjudicated Medicare lines (crossover)
- Fixable?
- N/A — informational; no action usually needed
- Typical fix
- Wait for the secondary crossover to pay; do not bill it manually
What does remark code MA18 mean?
Official X12 text (Alert): "The claim information is also being forwarded to the patient's supplemental insurer. Send any questions regarding supplemental benefits to them." Medicare processed the claim and automatically crossed it over to the Medigap or secondary plan on file. You do not have to bill the secondary yourself — the forward already happened.
ERA mini-example: 99213 (established E/M) pays $92.00 at Medicare with $18.40 in coinsurance moving to the patient's Medigap. MA18 appears on the remit, confirming Medicare forwarded the claim to the supplemental insurer, which will pay the coinsurance directly without a separate submission from you.
What does MA18 accompany?
MA18 is an Alert attached to adjudicated, usually paid, Medicare lines where a supplemental plan is on file — it does not ride a denial CARC. Its downstream counterpart is N522, which the secondary returns if you also bill it manually. Together they are a coordination of benefits signal. Confirm any accompanying codes in the denial code lookup.
How do you act on an MA18 alert?
- Note that the claim was crossed over — the secondary already has it, so no manual secondary claim is needed.
- Hold any auto-generated secondary billing for this claim to avoid a duplicate.
- Watch for the supplemental payer's remittance to post the coinsurance or deductible portion.
- Only if no secondary payment appears after a reasonable wait, and the plan has nothing on file, bill the secondary once with full primary payment detail.
How do you manage crossovers cleanly?
Make sure the patient's supplemental plan is on the Medicare crossover (COBA) file so the forward triggers reliably, and configure your system to recognize MA18 and hold manual secondary billing on those claims. Reconcile electronic remittance advice so posters can see the crossover payment arrive and close the balance. Clean crossover handling keeps coinsurance flowing to the secondary automatically without spawning duplicates.
Frequently asked questions
Usually no. MA18 confirms Medicare already forwarded the claim to the supplemental insurer through the crossover process, so the secondary will receive and adjudicate it automatically. Billing the secondary manually on top of that creates a duplicate, which typically comes back with N522. Wait for the crossover payment before doing anything.
MA18 on the Medicare remit is your confirmation that the forward occurred. Watch for the secondary payer's remittance to post the coinsurance or deductible portion. If, after a reasonable wait, no secondary payment appears and the supplemental plan has nothing on file, the crossover may have failed and you can then bill the secondary once with the primary payment detail.
MA18 is the Medicare-side alert that the claim was forwarded to the supplemental payer. N522 is what the secondary payer returns when you also send it a manual claim — a duplicate of the crossover. Seeing MA18 on the primary remit is your signal not to bill the secondary manually, precisely so you never generate an N522.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
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