Skip to main content

MA120 Remark Code: CLIA Number Missing or Invalid

MA120 means the claim for laboratory services did not have a valid CLIA certification number. Payers such as Medicare require the CLIA number of the lab that performed the test, so add or correct it and resubmit.

Quick facts

Code
MA120 (RARC MA120)
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 lab service was not paid because of the CLIA error. The provider corrects it; the patient is not billed.
Official description
Missing/incomplete/invalid CLIA certification number.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What MA120 means

Under the Clinical Laboratory Improvement Amendments (CLIA), labs that test human specimens must be certified. Medicare and many other payers require the lab’s CLIA certification number on claims for lab tests so they can confirm the lab is certified for the complexity of test billed. MA120 says the number was missing, incomplete, or invalid.

It typically accompanies CARC 16. If the number is valid but the certificate does not cover the test, the payer may use a different reason, such as CARC B7.

Common causes

  • Item 23 or the electronic CLIA reference was left blank.
  • The number was mistyped, or a prior certificate number was used after renewal.
  • A different lab’s CLIA number was reported, such as the reference lab instead of the in-office lab.
  • Item 23 contained another identifier, such as a prior authorization number.

How to fix it

  1. Look up your current CLIA certificate and confirm the number and certificate type.
  2. Report the CLIA number of the lab that performed the test in item 23 or the correct 837 segment.
  3. Check modifiers, such as QW for waived tests, where required.
  4. Resubmit the corrected claim, using resubmission code 7 with the original claim number in item 22 if it was processed.

How to prevent it

  • Store the CLIA number in your billing system so it populates automatically on lab claims.
  • Update records immediately when the certificate is renewed or changes type.
  • Separate claims with tests from different labs if payers require it.
  • A Claims Validator can flag lab claims without a CLIA number before submission.

Codes that may appear with MA120

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim is missing information needed for adjudication, identified by MA120 as the CLIA number.
  • CO-B7 (This provider was not certified/eligible to be paid for this procedure/service on this date of service.): The provider was not certified to be paid for this service, which can occur when the CLIA certificate does not cover the test.
  • MA110 (Missing/incomplete/invalid information on whether the diagnostic test(s) were performed by an outside entity or if no purchased tests are included…): The indicator for whether tests were purchased from an outside lab.
  • MA111 (Missing/incomplete/invalid purchase price of the test(s) and/or the performing laboratory's name and address.): The purchase price or performing lab's name and address.
  • MA108 (Paper claim contains more than one data item in field 23.): Too many data items in field 23, where Medicare expects the CLIA number on paper claims.

MA120 FAQ

Where does the CLIA number go?

For Medicare paper claims, the CLIA number goes in CMS-1500 item 23. On an 837, it is reported in the claim or line reference information for CLIA.

Do waived tests need a CLIA number?

Yes. Labs performing waived tests need a CLIA Certificate of Waiver, and Medicare generally requires the QW modifier on many waived tests.

What if the test was performed by a reference lab?

Report the CLIA number of the lab that performed the test, following your payer's rules for referred or purchased tests.