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MA04 Remark Code: Primary Payer Information Missing

MA04 means secondary payment cannot be considered because the claim did not identify the primary payer or did not include the primary payer's payment information, or the information was illegible. The secondary payer needs both before it can calculate what it owes.

Quick facts

Code
MA04 (RARC MA04)
Status
Active In use since January 1, 1997.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • OA (Other Adjustment): The claim is held back for coordination of benefits. The amount is neither a write-off nor patient responsibility until primary data is supplied.
  • CO (Contractual Obligation): Some payers report the missing primary information as a provider-responsible adjustment, but it is corrected by refiling with the primary payment details.
Official description
Secondary payment cannot be considered without the identity of or payment information from the primary payer. The information was either not reported or was illegible.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What MA04 means

When a patient has more than one insurer, the secondary payer calculates its payment based on what the primary payer allowed and paid. MA04 means the secondary payer could not do that math. Either the primary payer was not identified on the claim, its payment details were not included, or what you sent could not be read.

MA04 usually appears with CARC 22 under group OA. It is a coordination-of-benefits gap, not a coverage denial, so the claim can normally be refiled.

Common causes

  • The electronic claim to the secondary payer omitted the other-payer loops with the primary adjudication details.
  • A paper claim was sent without the primary EOB, or the copy was illegible.
  • Boxes 9 through 9d and 11d on the CMS-1500 were left blank or incomplete.
  • The primary payer’s claim was still pending when the secondary claim was sent.
  • The payer’s coordination-of-benefits record shows a different primary payer than the one you billed.

How to fix it

  1. Confirm the primary claim is finalised. Wait for the primary remittance before billing the secondary.
  2. Add the primary payer information. Include the primary payer’s identity and its paid amount and adjustments at the level they were reported.
  3. Resubmit the claim. Send a corrected or new claim to the secondary as the payer instructs, using resubmission code 7 in box 22 when replacing a processed claim.
  4. Attach a legible EOB for paper claims. Make sure the claim, patient, and dates on the EOB match.
  5. Fix the COB record if it is wrong. Ask the patient to update coverage order with their insurers when the payer lists the wrong primary.

How to prevent it

Collect all insurance cards at registration and confirm which plan is primary. Hold secondary claims until the primary remittance posts, then build the secondary claim from that data. Root causes are covered in eligibility and COB denials.

Codes that may appear with MA04

  • OA-22 (This care may be covered by another payer per coordination of benefits.): The care may be covered by another payer under coordination of benefits, which is the classic MA04 pairing.
  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim is missing information needed for adjudication, here the primary payer data.
  • N4 (Missing/Incomplete/Invalid prior Insurance Carrier(s)): The prior insurance carrier's EOB is missing, incomplete, or invalid.
  • N479 (Missing Explanation of Benefits (Coordination of Benefits or Medicare Secondary Payer).): Missing Explanation of Benefits for coordination of benefits or Medicare Secondary Payer claims.
  • MA92 (Missing plan information for other insurance.): Missing plan information for the other insurance, rather than missing payment information.
  • MA64 (Our records indicate that we should be the third payer for this claim.): The payer is third in line and needs payment information from both the primary and secondary payers.

MA04 FAQ

What information does the secondary payer need?

The primary payer's name and ID, and its adjudication results: the allowed amount, paid amount, and adjustments with their group and reason codes at claim or line level.

Can I just attach the primary EOB?

For paper claims many payers accept the primary EOB as an attachment. For electronic claims, send the primary adjudication data in the claim itself, since many payers will not match a separate EOB to an electronic claim.

Why did the claim not cross over automatically?

Automatic crossover depends on the primary payer having accurate secondary coverage information. If crossover failed, you need to bill the secondary payer directly.