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N109 Remark Code: Claim Chosen for Complex Review

N109 is an alert that the claim or service was selected for complex review, meaning a clinician at the payer or its contractor will examine the medical records before (or after) deciding payment. It is not itself a denial.

Quick facts

Code
N109 (RARC N109)
Status
Active In use since February 28, 2002; last modified July 1, 2015.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • OA (Other Adjustment): When the line is held or adjusted pending review, it may be shown as an other adjustment; the final liability depends on the review outcome.
  • CO (Contractual Obligation): If the review results in a denial, the provider-liability adjustment will appear on the resulting remittance.
Official description
Alert: This claim/service was chosen for complex review.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N109 means

N109 tells you a claim has been pulled for a closer look. In complex review, a clinical reviewer compares the medical record with the codes and coverage rules. The result can be full payment, partial payment, or denial, and it will be reported with its own reason and remark codes.

What to do

  1. Look for a records request. It will name the documents wanted and a due date.
  2. Send a complete, organized record for the dates of service: orders, notes, signatures, test results, and anything supporting medical necessity.
  3. Track the response date and confirm receipt with the reviewer if possible.
  4. Review the outcome when the claim is finalized, and appeal if the decision is not supported by the record.

If several claims from one provider or service line are selected, that is worth a documentation audit; the CARC and RARC analysis guide explains how to track review outcomes.

Codes that may appear with N109

  • OA-133 (The disposition of this service line is pending further review. (Use only with Group Code OA).): The disposition of the service is pending further review.
  • CO-226 (Information requested from the Billing/Rendering Provider was not provided or not provided timely or was insufficient/incomplete.): Used if records requested for the review were not provided or were insufficient.
  • N10 (Adjustment based on the findings of a review organization/professional consult/manual adjudication/medical advisor/dental advisor/peer review.): Reports an adjustment based on the findings of a review, often the outcome after N109.
  • M85 (Subjected to review of physician evaluation and management services.): Indicates evaluation and management services were subject to review.

N109 FAQ

What is the difference between complex and automated review?

Automated review applies system edits to claim data alone. Complex review involves a person, usually a nurse or physician reviewer, reading the medical records.

What should I do when I see N109?

Watch for an additional documentation request and answer it completely and on time. Missing the deadline is a common reason reviewed claims are denied.

Does N109 mean we did something wrong?

Not necessarily. Claims can be chosen through data analysis, targeted programs, or random sampling.