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MA129 Remark Code (Deactivated): Provider Not Certified

MA129 meant the provider was not certified to perform this procedure on the date of service. X12 deactivated it and suggested using remark MA120 together with reason code B7.

X12 deactivated RARCMA129 on January 31, 2004. Payers should no longer use it on new remittances, but it can still appear on older ERAs, corrected claims, and appeals.

Code: MA129 (RARC MA129)
Status: Deactivated StoppedJanuary 31, 2004 (in use since October 12, 2001).
Code set: Remittance Advice Remark Codes (RARC)
Group codes: CO (Contractual Obligation): Certification is the provider's responsibility, so the denied amount was not billed to the patient.
Official description: This provider was not certified for this procedure on this date of service.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What MA129 meant

Remark MA129 explained a denial based on certification: on the date the service was performed, the provider was not certified to perform that procedure. In practice this often involved laboratory testing, where a lab’s certification controls which tests it may bill.

What replaced it

X12’s note suggested combining two active codes: CO-B7, which says the provider was not certified or eligible to be paid for the procedure on that date, and MA120, the CLIA certification number remark. When the certification exists but does not cover the complexity of the test, payers use CO-B23.

If you still see MA129

It exists only in older data, and it was active only briefly. For a current certification denial, check the certificate or enrollment effective dates against the date of service and confirm the certificate covers the service. If it was in place, send proof and ask for reprocessing.

CO-B7 (This provider was not certified/eligible to be paid for this procedure/service on this date of service.): Part of the suggested replacement: provider not certified or eligible to be paid for this procedure on this date.
MA120 (Missing/incomplete/invalid CLIA certification number.): Part of the suggested replacement: missing, incomplete, or invalid CLIA certification number.
CO-B23 (Procedure billed is not authorized per your Clinical Laboratory Improvement Amendment (CLIA) proficiency test.): Procedure not authorized per the CLIA proficiency test.

MA129 FAQ

Why did X12 point to a CLIA remark?

Laboratory certification under CLIA was a common reason a provider was not certified for a test on a given date, so MA120 paired with B7 covered the typical case.

What if the certification issue is not lab-related?

CARC B7 still applies to any provider not certified or eligible for the service on that date. The payer may add a different remark code describing the specific certification.

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