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N431 Remark Code: Not Covered With This Procedure

N431 means the service is not covered when performed with the other procedure on the claim or in the patient's history for that date. It usually reflects a bundling or code-pair edit, such as an NCCI procedure-to-procedure edit, or a payer policy that excludes the combination.

Quick facts

Code
N431 (RARC N431)
Status
Active In use since November 5, 2007; last modified March 8, 2011.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The payer considers the service part of, or incompatible with, the other procedure. The amount is a provider adjustment and not billable to the patient.
Official description
Not covered with this procedure.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N431 means

N431 appears when two services meet on a claim and the payer will only pay for one of them. The service carrying N431 is not covered in combination with another procedure billed for the same patient and date, or one already processed. The paired CARC is usually 97 (included in another service), 236 (incompatible procedures), or 234 (not paid separately).

Common causes

  • Code-pair edits. The combination is listed in the National Correct Coding Initiative procedure-to-procedure edits or a payer’s equivalent bundling rules.
  • Component billed with its comprehensive code. A service that is part of a larger procedure was billed separately.
  • Missing or unsupported modifier. The services were separate, but the claim did not show it with an appropriate modifier such as 59 or an X modifier.
  • Split billing across claims or providers. The other procedure was billed on a different claim or by another provider in the same group, and the payer compared them.

How to fix it

  1. Identify the other procedure the payer paired with the denied line. Your remittance or the payer’s portal usually shows it.
  2. Look up the edit. For Medicare and many Medicaid programs, check the NCCI tables for the code pair and whether a modifier is allowed.
  3. Review the documentation. If the services were at a different anatomic site, a separate session, or a separate encounter, the record should say so.
  4. Correct the claim by adding the supported modifier to the right line and resubmitting with resubmission code 7, or by removing the bundled service if it was not separately reportable.
  5. Appeal if the payer’s edit does not apply as written, with the record and the edit source.

How to prevent it

Run code-pair checks at charge entry, not after denial. For a deeper walkthrough of edit types and modifiers, see NCCI denials and bundling. Claims Validator can flag common code-pair conflicts before submission.

Codes that may appear with N431

  • CO-97 (The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.): The benefit is included in the payment for another service already adjudicated.
  • CO-236 (This procedure or procedure/modifier combination is not compatible with another procedure or procedure/modifier combination provided on the same day…): The procedure or procedure-modifier combination is not compatible with another procedure on the same day.
  • CO-234 (This procedure is not paid separately.): The procedure is not paid separately.
  • N19 (Procedure code incidental to primary procedure.): The procedure is incidental to the primary procedure.
  • N20 (Service not payable with other service rendered on the same date.): The service is not payable with another service rendered on the same date.
  • M80 (Not covered when performed during the same session/date as a previously processed service for the patient.): Not covered when performed in the same session or date as a previously processed service.
  • N356 (Not covered when performed with, or subsequent to, a non-covered service.): Not covered when performed with, or after, a non-covered service.

N431 FAQ

Is N431 always an NCCI edit?

No. NCCI edits are a common source, but commercial payers also apply their own bundling policies. The paired CARC and the payer's policy tell you which applies.

Will adding modifier 59 fix it?

Only if the services were truly distinct, such as a separate site, session, or encounter, and the edit allows a modifier. Adding it without documentation to support it is not appropriate.

Which line gets denied?

Usually the column two or secondary code in the pair. If the payer denied the higher-value service instead, review how the lines were ordered and coded.