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MA42 Remark Code: Missing or Invalid Admission Source

MA42 means the admission source, now usually called the point of origin for admission or visit, is missing, incomplete, or invalid. The payer needs to know where the patient came from, such as a physician referral, another hospital, or a nursing facility.

Quick facts

Code
MA42 (RARC MA42)
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 facility must correct the claim. The patient is not billed for a claim returned for invalid admission data.
Official description
Missing/incomplete/invalid admission source.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What MA42 means

MA42 concerns the start of the patient’s journey. The admission source describes how the patient arrived: referred by a physician or clinic, transferred from another hospital or a skilled nursing facility, via court or law enforcement, and so on. Payers rely on it to apply transfer and readmission policies. MA42 says the code was missing or unusable.

It is the counterpart to MA43, which covers the end of the stay.

Common causes

  • Form locator 15 was left blank.
  • A retired or invalid point of origin code was used.
  • The source conflicts with other data, such as a transfer source with no transfer history, or a newborn source on an adult patient.
  • Registration captured an arrival method but did not map it to the standard code set.

How to fix it

  1. Confirm how the patient arrived from registration notes and transfer paperwork.
  2. Correct form locator 15 with a valid point of origin code.
  3. Check related fields such as admission type and transfer-related condition codes.
  4. Resubmit the corrected claim.

How to prevent it

Map every registration arrival option to a valid point of origin code and review the mapping when the code set changes. For a broader look at header-data problems, see how to analyze CARC and RARC codes.

Codes that may appear with MA42

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): Claim information is missing or invalid, and MA42 names the admission source.
  • MA41 (Missing/incomplete/invalid admission type.): The admission type, the priority of admission, is missing or invalid.
  • MA43 (Missing/incomplete/invalid patient status.): The patient status, meaning where the patient went at discharge, is missing or invalid.
  • MA40 (Missing/incomplete/invalid admission date.): The admission date is missing or invalid.

MA42 FAQ

Where is the admission source reported?

Form locator 15 on the UB-04, titled Point of Origin for Admission or Visit. On an 837I it is the admission source code in the institutional claim code segment.

Why does the source matter for payment?

It can affect transfer rules, readmission reviews, and how the payer treats related services. For example, a transfer from another hospital may be handled differently from a physician referral.

Is the source needed on outpatient claims?

Many payers require the point of origin on outpatient claims as well as inpatient ones. Check the payer's instructions for your bill type.