Skip to main content

MA31 Remark Code: Invalid Statement Period Dates

MA31 means the beginning and ending dates of the period billed, the statement covers period, are missing, incomplete, or invalid. The payer needs a valid from and through date to know which days the claim covers.

Quick facts

Code
MA31 (RARC MA31)
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 provider must correct the dates. The patient should not be billed for a claim returned with invalid statement dates.
Official description
Missing/incomplete/invalid beginning and ending dates of the period billed.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What MA31 means

Every institutional claim declares the span of days it covers, from the first day to the last. MA31 says that span is absent or does not make sense: a missing date, an impossible date, a through date before the from date, or dates that do not agree with other parts of the claim.

The statement period frames everything else on the claim, including covered days, line-item dates, and the frequency code in the type of bill, so an error here tends to cascade.

Common causes

  • The through date is earlier than the from date.
  • Service line dates fall outside the statement period.
  • A claim crosses a boundary the payer requires to be billed separately, such as a calendar month or fiscal year.
  • Interim bills use dates that do not continue from the previous interim claim.
  • Future dates were entered for services not yet provided.

How to fix it

  1. Review form locator 6 or the 837I statement dates.
  2. Compare with line-level dates and the admission and discharge dates.
  3. Split the claim if the payer requires separate periods.
  4. Resubmit with valid dates, using the replacement frequency code if the original claim was processed.

How to prevent it

Generate statement dates automatically from the encounter or account dates instead of keying them. For more on stopping errors before they reach the payer, see claim rejection vs. denial.

Codes that may appear with MA31

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): Information needed to process the claim is missing, and MA31 points to the statement period.
  • MA40 (Missing/incomplete/invalid admission date.): The admission date is missing or invalid, a different date on inpatient claims.
  • MA30 (Missing/incomplete/invalid type of bill.): The type of bill is missing or invalid; its frequency digit must match how the period is billed.
  • MA32 (Missing/incomplete/invalid number of covered days during the billing period.): The number of covered days is missing or invalid, which must fit inside the statement period.

MA31 FAQ

Where are the statement dates on a UB-04?

Form locator 6, Statement Covers Period, holds the from and through dates. On an 837I they are reported as the statement date range at claim level.

Can the statement period span two months?

It depends on the claim type and payer. Some institutional claims must be split by month or by other boundaries. Check the payer's rules for the bill type.

What if a line date falls outside the period?

Payers usually reject or deny that line or the claim. All service dates should fall within the statement covers period.