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N39 Remark Code: Procedure Doesn't Fit Tooth Number

N39 means the procedure code is not compatible with the tooth number or letter reported. The payer's edits found that the procedure cannot be performed on, or is not appropriate for, that tooth.

Quick facts

Code
N39 (RARC N39)
Status
Active In use since January 1, 2000.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The line is denied as a coding conflict the provider must correct. It is not billable to the patient.
  • PI (Payer Initiated Reduction): Some government dental programs report it as a payer-initiated adjustment.
Official description
Procedure code is not compatible with tooth number/letter.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N39 means

Many dental procedure codes are defined for a certain kind of tooth: anterior or posterior, primary or permanent, or a specific number of canals or roots. Payer edits compare the procedure on each line with the tooth reported. When they do not fit together, the payer returns N39.

Unlike N37, the tooth field is filled in. The issue is that the combination makes no sense to the payer’s system. N39 is usually paired with CARC 16.

Common causes

  • A procedure code for anterior teeth was billed with a posterior tooth number, or vice versa.
  • A primary tooth letter was used with a procedure meant for permanent teeth.
  • The wrong procedure code was selected in the charting software, such as a premolar code on a molar.
  • A tooth number was mistyped (for example, 13 instead of 31).
  • A procedure normally performed per arch or quadrant was reported with a single tooth number.

How to fix it

  1. Check the chart for the tooth treated and the exact procedure.
  2. Decide which element is wrong. Either the tooth number or the procedure code needs to change.
  3. Correct the line on the dental claim and verify related fields like surfaces and quadrant.
  4. Resubmit as a corrected dental claim, following the payer’s process.
  5. Appeal with records if both are correct and the payer’s edit is too strict.

How to prevent it

Use practice management software that restricts procedure selection to codes valid for the charted tooth. Review claims with manually entered tooth numbers before submission, especially for patients with mixed dentition.

Codes that may appear with N39

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): A billing error; N39 identifies a mismatch between procedure and tooth.
  • CO-4 (The procedure code is inconsistent with the modifier used.): The procedure code is inconsistent with a modifier or related indicator on the line.
  • CO-6 (The procedure/revenue code is inconsistent with the patient's age.): The procedure is inconsistent with the patient's age, which can overlap with primary vs permanent tooth errors.
  • N37 (Missing/incomplete/invalid tooth number/letter.): The tooth number is missing or invalid, rather than mismatched.
  • N81 (Procedure billed is not compatible with tooth surface code.): The procedure is not compatible with the tooth surface code.
  • N384 (Records indicate that the referenced body part/tooth has been removed in a previous procedure.): The referenced tooth has been removed in a previous procedure.

N39 FAQ

What is an example of an incompatible tooth number?

Billing a procedure defined for anterior teeth on a molar, or a procedure for permanent teeth on a primary tooth letter, are typical mismatches payers flag.

What if the procedure really was done on that tooth?

If the procedure code is correct and clinically appropriate, send the chart notes and radiographs with an appeal or reconsideration request explaining the situation.

Is N39 related to the patient's age?

Sometimes. A child can have both primary and permanent teeth, so the right tooth designation, and the right procedure code, depends on which tooth was actually treated.