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N253 Remark Code: Attending Provider NPI Invalid

N253 means the attending provider's primary identifier, which is the National Provider Identifier (NPI), was missing, incomplete, or invalid on the claim. The payer could not tie the attending role to a valid, recognized clinician.

Quick facts

Code
N253 (RARC N253)
Status
Active In use since December 2, 2004.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): A correctable claim error. The facility writes off nothing yet; it fixes the NPI and resubmits, and the patient is not billed for the adjustment.
Official description
Missing/incomplete/invalid attending provider primary identifier.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N253 means

Institutional claims identify the attending physician by NPI. On the UB-04 that number sits in form locator 76; on the 837I it goes with the attending provider details. When the payer’s edit cannot read or accept that number, it returns N253, usually with CARC 16 or one of the NPI-specific reason codes (206, 207, or 208).

Because the payer never matched the attending clinician, it did not evaluate the service for coverage. Once the identifier is right, the claim can process normally.

Common causes

  • The attending NPI was left blank when the claim was generated from an admission that had no attending assigned.
  • The facility’s own organizational NPI was dropped into the attending field.
  • A digit was mistyped, breaking the NPI check digit.
  • The physician’s NPI was deactivated in NPPES, or it belongs to someone else with a similar name.
  • A resident or temporary physician without enrollment was listed as attending.

How to fix it

  1. Confirm the attending physician for the claim period from the discharge summary or order record.
  2. Verify the NPI in the NPPES registry: active status, individual (Type 1) entity, and correct name.
  3. If the physician must be enrolled with this payer, confirm enrollment before rebilling. Our article on NPI, TIN, and enrollment denials explains what to look for.
  4. Update the provider record in your billing system.
  5. Submit a replacement claim with frequency code 7 and the original payer claim number. If the payer treated the first claim as unprocessable, a new claim may be required instead.

How to prevent it

  • Require an attending NPI at the point the account is finalized, not only at billing.
  • Validate the NPI check digit automatically and reject Type 2 (organization) NPIs in individual roles.
  • Re-verify physician NPIs against NPPES on a schedule, especially for locum and per-diem staff.

Codes that may appear with N253

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): Missing or invalid claim information, narrowed by N253 to the attending provider NPI.
  • CO-206 (National Provider Identifier - missing.): Reports that an NPI is missing entirely.
  • CO-207 (National Provider identifier - Invalid format): Reports that an NPI failed its format or check-digit test.
  • CO-208 (National Provider Identifier - Not matched.): Reports that the NPI does not match the payer's records for that provider.
  • N252 (Missing/incomplete/invalid attending provider name.): Points to the attending provider's name instead of the identifier.
  • N254 (Missing/incomplete/invalid attending provider secondary identifier.): Points to the attending provider's secondary identifier, such as a state license or payer-assigned number.
  • N290 (Missing/incomplete/invalid rendering provider primary identifier.): The equivalent NPI problem for the rendering provider on professional claims.

N253 FAQ

What counts as the attending provider's primary identifier?

For HIPAA standard transactions the primary identifier is the individual's 10-digit NPI. Group or facility NPIs should not be used in the attending role.

How can an NPI be invalid if it is 10 digits?

The last digit is a check digit calculated from the others, so a typo can make the number fail validation. A valid NPI can also be deactivated or not enrolled with the payer.

Is N253 the same as an enrollment denial?

Not necessarily. N253 is about the data element. If the NPI is valid but the physician is not enrolled, the payer may use a different reason, such as CARC B7 or 185.