What does denial code 109 mean and how can I address it?

Name: CO 109 Denial Code: What It Means and How to Fix It
Uploaded: 2026-03-06T21:15:01+00:00
Duration: 3 min 15 s

Editorial team InsuredAndMore.com Published on October 21, 2026

Denial code 109 (often formatted as CO-109) means that the claim or service is not covered by the billed payer or contractor, and you must send the claim to the correct insurance payer.

What Denial Code 109 Means

Wrong Payer: The claim was submitted to the wrong insurance company or the wrong Medicare contractor.
Coordination of Benefits (COB): Another insurer is primary and should have been billed first before the current payer.
No Patient Liability: This is a routing or coverage sequence error, meaning the patient is not automatically responsible for the balance.

How to Address It

Review the Remittance Advice: Check for any accompanying remark codes (such as N104 or N418) to identify the specific jurisdiction or correct contractor details.
Verify Patient Insurance: Recheck the patient's active coverage, effective dates, and coordination of benefits to find the true primary insurance.
Correct and Resubmit: Update the billing records with the correct primary or secondary payer information and submit the clean claim to the appropriate entity.