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MA100 Remark Code: Date of Current Illness Missing

MA100 means the claim's date of current illness or symptoms was missing, incomplete, or invalid. Payers need it for certain services, such as injury-related care or treatment where onset determines coverage.

Quick facts

Code
MA100 (RARC MA100)
Status
Active In use since January 1, 1997; last modified March 14, 2014.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The claim was not processed because the onset date was missing or invalid. The provider corrects it; the patient is not billed.
Official description
Missing/incomplete/invalid date of current illness or symptoms.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What MA100 means

MA100 tells you the date of current illness, injury, or symptoms on the claim was missing, incomplete, or invalid. Payers use this date to judge whether care relates to a new condition or an ongoing one, to connect claims to an accident, and to apply limits that depend on when a condition began. On paper claims it is CMS-1500 item 14, with a qualifier that explains which kind of date it is.

It typically accompanies CARC 16.

Common causes

  • Item 14 was blank on a claim type the payer requires it for.
  • The qualifier was missing, so the payer could not interpret the date.
  • The onset date was after the date of service, which is illogical.
  • The date was entered in the wrong item, such as the injury or initial treatment field.
  • The electronic claim did not carry the date segment.

How to fix it

  1. Check the medical record for the documented onset date.
  2. Enter the date with the correct qualifier in item 14 or the equivalent 837 segment.
  3. Confirm consistency with other dates on the claim, such as the date of service and accident date.
  4. Resubmit. Send a new claim if the original was rejected, or use resubmission code 7 with the original claim number in item 22 to replace a processed claim.

How to prevent it

  • Capture onset dates during intake for injury, chiropractic, and therapy patients.
  • Set an edit requiring item 14 for the claim types your payers require it on.
  • A pre-submission Claims Validator can flag missing or illogical dates. For more on this type of denial, see CO-16 missing information denials.

Codes that may appear with MA100

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim is missing required information, and MA100 identifies the onset date.
  • N305 (Missing/incomplete/invalid injury/accident date.): A missing or invalid injury or accident date, a separate date field.
  • MA122 (Missing/incomplete/invalid initial treatment date.): A missing or invalid initial treatment date.
  • MA121 (Missing/incomplete/invalid x-ray date.): A missing or invalid x-ray date, used on chiropractic claims.

MA100 FAQ

Where does the date of current illness go?

On the CMS-1500 it goes in item 14, with a qualifier identifying the date type, such as onset of current symptoms or illness, or last menstrual period.

Which claims need it?

It depends on the payer and service. It is commonly required for injury-related claims, chiropractic, and certain therapy services. Check your payer's instructions.

What if the patient doesn't remember the exact date?

Use the best date documented in the record. Payers generally expect the onset date to be supported by the documentation and not after the date of service.