MA40 remark code

Remittance advice remark code MA40. Remark codes add detail to the reason code on the same claim line.

Missing or invalid admission date

Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated Nov 11, 2026.

What MA40 means

The admission date on an institutional claim is missing, incomplete or not valid.

The payer needs the admission date to place an inpatient or related claim in the right time frame. This remark says the date was missing, invalid, or did not fit the statement period.

It usually comes with reason code 16 and is fixed with a corrected claim.

Common causes

• The admission date was left blank on an inpatient claim.
• The admission date falls after the statement period starts.
• The registration system recorded the wrong date for the admission.

What to do next

1. Confirm the admission date in the registration and medical record.
2. Check that it is consistent with the statement period on the claim.
3. Send a corrected claim with the confirmed admission date.

Related codes

• 16 (reason code) Missing information or billing error
• MA31 (remark code) Missing or invalid billing period dates
• MA133 (remark code) Dates fall inside an inpatient stay