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MA99 Remark Code: Medigap Information Missing or Invalid

MA99 means the Medigap (Medicare Supplement) information on the claim was missing, incomplete, or invalid. Medicare uses those details to forward the claim to the patient's Medigap insurer.

Quick facts

Code
MA99 (RARC MA99)
Status
Active In use since January 1, 1997; last modified February 28, 2003.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The Medigap data error is the provider's to correct. Medicare's own processing is not the patient's responsibility to fix.
  • PR (Patient Responsibility): Patient cost-sharing on the line stays open until the Medigap insurer receives and processes the claim.
Official description
Missing/incomplete/invalid Medigap information.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What MA99 means

Medigap policies are private Medicare Supplement plans that help pay a patient’s Medicare cost-sharing. When a participating provider lists Medigap information on a Medicare claim, Medicare can send the processed claim to that insurer automatically. MA99 says the Medigap information on the claim was missing, incomplete, or invalid.

On Medicare remittances, it most often means the Medigap fields could not be used for crossover, and it may come with CARC 16.

Common causes

  • Item 9d did not contain a valid Medigap insurer identifier.
  • The policy number in item 9a was blank or incorrect.
  • A non-Medigap plan, such as an employer retiree plan, was entered in the Medigap fields.
  • Item 9 fields were partially completed, with the enrollee’s name missing.

How to fix it

  1. Confirm the plan is Medigap by checking the patient’s supplement card.
  2. Complete items 9, 9a, and 9d using the insurer identifier your Medicare contractor recognizes.
  3. Bill the Medigap insurer directly if Medicare already processed the claim and did not forward it.
  4. Correct the account so future claims carry complete Medigap data.

How to prevent it

  • Keep a list of Medigap insurer identifiers accepted by your Medicare contractor.
  • Separate Medigap from other secondary coverage in your registration system.
  • More on routing secondary claims: eligibility and COB denials.

Codes that may appear with MA99

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim has missing or invalid information, with MA99 pointing to the Medigap fields.
  • PR-2 (Coinsurance Amount): Coinsurance that the Medigap plan would normally consider after Medicare pays.
  • MA92 (Missing plan information for other insurance.): Missing plan information for other insurance generally, not specifically Medigap.
  • MA68 (Alert: We did not crossover this claim because the secondary insurance information on the claim was incomplete.): Crossover did not happen because secondary insurance information was incomplete.
  • MA18 (Alert: The claim information is also being forwarded to the patient's supplemental insurer.): The claim was successfully forwarded to the supplemental insurer.

MA99 FAQ

Where does Medigap information go on the CMS-1500?

Medicare's instructions use item 9 (Medigap enrollee's name), 9a (policy or group number), and 9d (the Medigap insurer identifier). Item 9 fields are used only for Medigap on Medicare claims.

Does Medigap information affect my Medicare payment?

Usually not. It controls whether Medicare forwards the claim to the Medigap insurer. Your Medicare payment is determined separately.

What if the patient's supplemental plan is not Medigap?

Other supplemental coverage, such as employer retiree plans, is reported differently. Only true Medigap policies go in the Medigap fields.