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N291 Remark Code: Rendering Provider Secondary ID

N291 means the rendering provider's secondary identifier was missing, incomplete, or invalid. It is an ID other than the NPI, such as a state license number or payer-assigned provider number, that some payers require for the clinician who performed the service.

Quick facts

Code
N291 (RARC N291)
Status
Active In use since December 2, 2004; last modified November 1, 2010.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): Provider-correctable; supply or fix the secondary ID and resubmit. Not billable to the patient.
Official description
Missing/incomplete/invalid rendering provider secondary identifier.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N291 means

Each service line on a CMS-1500 has room for a rendering provider NPI (unshaded 24J) and, above it, an optional qualifier and secondary identifier (shaded 24I and 24J). A few payers still require that secondary value, for example a Medicaid provider number or a license. N291 tells you it was missing or couldn’t be read.

The X12 code list shows this remark was modified in 2010. It is normally paired with CARC 16 and handled with a corrected claim.

Common causes

  • A payer requiring a rendering secondary ID was set up in your system without that requirement.
  • The qualifier and number don’t agree, for instance a license number sent under a payer-ID qualifier.
  • Only the identifier was sent, without any qualifier.
  • The number is from a different state, has expired, or was reissued.
  • A secondary ID is being sent to a payer that no longer accepts them, and it rejects the unexpected value.

How to fix it

  1. Look up the payer’s requirements for rendering provider identifiers.
  2. Get the correct number from credentialing records or the payer.
  3. Populate the qualifier and number for that clinician and payer only.
  4. If the payer doesn’t need a secondary ID, clear the field entirely.
  5. Resubmit with frequency code 7 and the original claim number.

How to prevent it

Keep a table of which payers want rendering secondary IDs and which type. Link it to credentialing so license renewals update billing automatically. When N291 appears for several clinicians with the same payer, fix the payer-level rule rather than correcting claims one by one; our CARC and RARC analysis guide explains how to spot that pattern.

Codes that may appear with N291

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim lacks information; N291 names the rendering provider's secondary identifier.
  • N290 (Missing/incomplete/invalid rendering provider primary identifier.): The rendering provider's NPI is the problem.
  • N288 (Missing/incomplete/invalid rendering provider taxonomy.): The rendering provider's taxonomy is the problem; it uses the same shaded boxes with a different qualifier.
  • N287 (Missing/incomplete/invalid referring provider secondary identifier.): The referring provider's secondary identifier is the problem.
  • N433 (Resubmit this claim using only your National Provider Identifier (NPI).): Tells you to resubmit using only the NPI.

N291 FAQ

Where does a rendering secondary ID go on paper?

The qualifier goes in the shaded top of box 24I, and the identifier goes in the shaded top of box 24J, above the NPI.

What qualifiers are used?

The qualifier describes the ID type, such as a state license or a payer-assigned number. Use the one the payer's instructions specify for its identifier.

Is a taxonomy code a secondary ID?

It uses the same shaded area with the ZZ qualifier, but payers treat taxonomy separately. A taxonomy problem is usually reported as N288, not N291.