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MA61 Remark Code: Missing or Invalid Social Security Number

MA61 means the Social Security number the payer needs on this claim is missing, incomplete, or invalid. Payers that identify members or other parties by SSN cannot process the claim until a valid number is supplied.

Quick facts

Code
MA61 (RARC MA61)
Status
Active In use since January 1, 1997; last modified March 1, 2018.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The provider must correct the claim. The patient is not billed because of a missing identifier.
Official description
Missing/incomplete/invalid social security number.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What MA61 means

Some payers still identify members, insured parties, or other individuals by Social Security number. When the claim is missing that number, or the number has the wrong length or an impossible pattern, the payer returns MA61.

For Medicare, beneficiary identifiers are no longer based on SSNs, so MA61 on a Medicare claim usually signals that an outdated or incorrect identifier was used rather than a request to add an SSN.

Common causes

  • The ID field was left blank for a payer that uses the SSN as the member ID.
  • Digits were transposed or dropped.
  • A dependent’s claim used the dependent’s SSN where the payer expects the insured’s, or the reverse.
  • An old SSN-based identifier was used after the payer switched to member numbers.

How to fix it

  1. Check the payer’s ID requirements and the patient’s current card.
  2. Correct box 1a or the relevant identifier field, making sure the number belongs to the correct person.
  3. Resubmit the claim; if the original was processed, follow the payer’s corrected-claim rules with resubmission code 7 in box 22.

How to prevent it

Store identifiers securely, verify them with an eligibility check, and limit SSN use to payers that require it. Identifier format checks are a good fit for a Claims Validator before submission.

Codes that may appear with MA61

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): Required information is missing or invalid, with MA61 naming the Social Security number.
  • CO-31 (Patient cannot be identified as our insured.): The patient cannot be identified as the payer's insured.
  • MA27 (Missing/incomplete/invalid entitlement number or name shown on the claim.): The entitlement number or name is missing or invalid, which applies to Medicare IDs.
  • MA21 (SSA records indicate mismatch with name and sex.): Name and sex do not match Social Security records.
  • MA36 (Missing/incomplete/invalid patient name.): The patient name is missing or invalid.

MA61 FAQ

Does Medicare still use Social Security numbers?

Medicare replaced SSN-based identifiers with the Medicare Beneficiary Identifier. If you receive MA61 on a Medicare claim, check whether an outdated identifier was used.

Which payers may ask for an SSN?

Some commercial, workers' compensation, and government programs still identify members or insured parties by SSN. Follow each payer's instructions.

Where is the member identifier entered?

On the CMS-1500, box 1a holds the insured's ID number. Enter whatever identifier the payer assigns, whether an SSN or a member number.