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M57 Remark Code (Deactivated): Provider Identifier

M57 meant a provider identifier on the claim was missing, incomplete, or invalid, without saying which provider's. X12 deactivated it without naming a replacement; payers now use remarks for each role, such as N257 for the billing provider or N290 for the rendering provider.

X12 deactivated RARCM57 on June 2, 2005. Payers should no longer use it on new remittances, but it can still appear on older ERAs, corrected claims, and appeals.

Code: M57 (RARC M57)
Status: Deactivated StoppedJune 2, 2005 (in use since January 1, 1997).
Code set: Remittance Advice Remark Codes (RARC)
Group codes: CO (Contractual Obligation): Usually accompanied CARC 16 under CO, as identifiers are the provider's responsibility.
Official description: Missing/incomplete/invalid provider identifier.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What M57 meant

Remark M57 was the generic “provider identifier problem” message. Some provider number on the claim was blank, malformed, or not recognized. The billing office had to work out which one by checking each identifier on the claim.

What replaced it

X12 did not name a successor. Current remarks specify the provider role, which saves that detective work. Common ones include N257 for the billing provider, N290 for the rendering provider, and N286 for the referring provider. They usually accompany CARC CO-16.

If you still see M57

It dates from before NPIs were standard, so you will only find it in archived data. For a current identifier remark, verify every NPI and taxonomy on the claim against NPPES and the payer’s enrollment, fix the one that does not match, and resubmit.

N257 (Missing/incomplete/invalid billing provider/supplier primary identifier.): Missing, incomplete, or invalid billing provider or supplier primary identifier.
N290 (Missing/incomplete/invalid rendering provider primary identifier.): Missing, incomplete, or invalid rendering provider primary identifier.
N286 (Missing/incomplete/invalid referring provider primary identifier.): Missing, incomplete, or invalid referring provider primary identifier.
CO-16 (Claim/service lacks information or has submission/billing error(s).): The adjustment code these remarks usually accompany.

M57 FAQ

Why was M57 retired?

It did not say which provider's identifier was wrong. Claims can list billing, rendering, referring, ordering, supervising, and facility providers, so role-specific remarks make the fix obvious.

What is the most common cause today?

An NPI that is not linked to the payer's enrollment record for that provider or location, or an individual NPI where an organizational one is expected, or the reverse.

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