N31 remark code

Remittance advice remark code N31. Remark codes add detail to the reason code on the same claim line.

Prescribing provider ID problem

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 N31 means

The identifier for the provider who prescribed the item or drug is missing, incomplete or not valid on the claim.

Claims for drugs, supplies and equipment often require the prescriber's NPI. N31 means the payer could not find a usable prescribing provider identifier, so it could not verify who ordered the item.

This remark adds detail to a missing or invalid information reason code, commonly 16, and is typically fixed with a corrected claim.

Common causes

• The prescriber field was left blank on a pharmacy, DME or infusion claim.
• The prescriber NPI was mistyped or belongs to an organization rather than an individual.
• The prescriber is not enrolled or not active with the payer.

What to do next

1. Check the order or prescription for the prescriber's name and individual NPI.
2. Verify the NPI in the national registry and confirm it is active.
3. Resubmit a corrected claim with the prescriber information in the correct field.
4. Ask the prescriber to enroll with the payer if enrollment is required for ordering.

Related codes

• N265 (remark code) Ordering provider ID problem
• N574 (remark code) Ordering provider type not allowed
• 16 (reason code) Missing information or billing error