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N31 Remark Code: Invalid Prescribing Provider ID

N31 means the identifier for the prescribing provider was missing, incomplete, or invalid. Claims for prescribed items, such as drugs, durable medical equipment, and some supplies, must identify the practitioner who prescribed them, usually by NPI.

Code: N31 (RARC N31)
Status: Active In use since January 1, 2000; last modified December 2, 2004.
Code set: Remittance Advice Remark Codes (RARC)
Group codes: CO (Contractual Obligation): The claim is denied for a correctable billing error. It is not the patient's responsibility.
PI (Payer Initiated Reduction): A payer-initiated adjustment, seen with some government programs. Correcting the prescriber data resolves it.
Official description: Missing/incomplete/invalid prescribing provider identifier.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What N31 means

When a claim is for something a practitioner prescribed, such as a medication, a wheelchair, oxygen, or diabetic supplies, the payer needs to know who wrote the prescription. N31 says the payer could not identify that prescriber from the claim: the ID was blank, truncated, or not one the payer accepts.

It most often explains CARC 16. When the ID is readable but the prescriber is not allowed to prescribe the item, CARC 184 may appear instead.

Common causes

The prescription listed a practitioner’s name but no NPI, and staff did not look it up.
The NPI of the supplier, clinic, or a group was entered instead of the individual prescriber.
The prescriber’s NPI was mistyped or has been deactivated.
The prescriber is not enrolled with the payer, which some programs require for ordering and prescribing.
The prescriber data was placed in the wrong claim field.

How to fix it

Get the prescription or order and confirm the prescriber’s full name and credentials.
Look up the individual NPI in the NPPES registry and confirm it is active.
Check payer enrollment if the program requires prescribers to be enrolled or approved.
Correct the claim. On a CMS-1500, report the prescriber in box 17 with the right qualifier and the NPI in box 17b, or use the prescriber fields in your electronic or pharmacy format.
Submit a corrected claim with resubmission code 7, or reverse and rebill for pharmacy claims.

How to prevent it

Capture the prescriber’s NPI at intake for every prescription-based order, and validate it against the registry before billing. Pre-submission checks in Claims Validator can catch blank or malformed prescriber identifiers. For more on identifier issues, read provider enrollment and NPI denials.

Codes that may appear with N31

CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim lacks required information, and N31 names the prescriber identifier.
CO-184 (The prescribing/ordering provider is not eligible to prescribe/order the service billed.): The prescribing or ordering provider is not eligible to prescribe or order the item billed.
CO-208 (National Provider Identifier - Not matched.): The NPI reported did not match the payer's records.

N265 (Missing/incomplete/invalid ordering provider primary identifier.): The ordering provider's primary identifier is missing or invalid, used for ordered tests and services.
N57 (Missing/incomplete/invalid prescribing date.): The prescribing date is missing or invalid.
N286 (Missing/incomplete/invalid referring provider primary identifier.): The referring provider's primary identifier is missing or invalid.
N544 (Alert: Although this was paid, you have billed with a referring/ordering provider that does not match our system record.): Alert that the referring or ordering provider on a paid claim does not match the payer's records.

N31 FAQ

Can I use my own NPI as the prescriber?

Only if you actually wrote the prescription or order. A supplier or pharmacy must report the practitioner who prescribed the item, not itself.

What makes a prescriber ID invalid?

A wrong or deactivated NPI, a prescriber type the payer does not allow for that item, or a name that does not match the NPI registry. Some payers also require the prescriber to be enrolled with them.

Where does the prescriber go on a professional claim?

On a CMS-1500, the ordering or prescribing practitioner is typically reported in box 17 with the proper qualifier and the NPI in box 17b. Pharmacy claims carry the prescriber ID in the pharmacy claim format.

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