CO-109 Denial Code: Claim Not Covered by This Payer

The payer is telling you that it is not responsible for this claim and that it belongs with another payer or contractor. This happens frequently with Medicare Advantage members billed to traditional Medicare, Medicaid managed care members billed to fee-for-service Medicaid, and plans that carve out behavioral health or other services to a separate administrator.

The group code (CO, PR, OA, PI) tells you who is responsible. The CARC number tells you why.

CO-109 means you sent the claim to the wrong payer or contractor. Identify who actually covers the service, such as a Medicare Advantage plan, a behavioral health carve-out, or a different Medicare contractor, and resubmit there before timely filing runs out.

Common causes of CO-109.

• Patient enrolled in Medicare Advantage but claim billed to traditional Medicare
• Behavioral health, vision, or other services carved out to a separate plan administrator
• Medicaid managed care versus fee-for-service confusion
• Durable medical equipment billed to the wrong Medicare contractor
• Outdated payer ID in the practice management system

How to work a CO-109 denial.

The order matters: confirm the facts before deciding between a corrected claim, a reconsideration, or an adjustment.

1. 1Run eligibility and review plan-level details for carve-outs or managed care enrollment.
2. 2Identify the correct payer and payer ID for the service.
3. 3Submit the claim to the correct payer promptly. Keep the original submission records in case you need to show timely filing.
4. 4Update the patient's insurance record and payer ID mapping.

How to keep CO-109 from coming back.

• Maintain a list of plans that carve out services you provide
• Check eligibility responses for managed care or Medicare Advantage enrollment
• Review payer ID mappings when payers merge or change

Fixing this at the source usually sits with eligibility verification →

Questions about CO-109.

Denials that often travel with this one.

Browse all denial codes →

Add a Dedicated Denial Specialist

RCM Staff places trained denial management specialists inside your EHR and clearinghouse to work the queue, correct and appeal claims, and track root causes by payer.