CO-109: Claim Not Covered by This Payer

What Does CO-109 Mean?

With CO (Contractual Obligation), the CARC 109 adjustment is the provider's responsibility. The payer denied or reduced payment because of the claim was sent to a MAC that does not have jurisdiction over the provider's geographic area or service type, and must be resubmitted to the correct MAC. The patient is not liable for this amount.

CARC 109 appears on a remittance when the payer applies an adjustment for claim not covered by this payer. Review the group code and any accompanying RARC codes to understand the full context of this adjustment.

Common scenarios that trigger this adjustment include: the claim was sent to a MAC that does not have jurisdiction over the provider's geographic area or service type, and must be resubmitted to the correct MAC; The patient's insurance coverage is with a different plan or payer than the one the claim was submitted to; The specific service type (Part A vs. Part B, DME vs. professional) was submitted to a payer that does not process that category of claims. The group code paired with CARC 109 determines who bears the financial responsibility — CO places it on the provider as a contractual obligation, OA indicates a coordination of benefits or other payer adjustment, PR shifts it to the patient.

Common Causes

How to Resolve

1. Review the remittance details Examine the CO-109 adjustment and any accompanying RARC codes to identify the specific reason for the denial.
2. Identify the root cause Determine which issue applies: claim submitted to wrong Medicare contractor (MAC), patient not covered by this specific plan or payer, service type not covered under this contract, among others.
3. Correct the claim Address the identified issue — update the claim data in your billing system to resolve the claim not covered by this payer problem.
4. Resubmit the corrected claim Submit the corrected claim following the payer's resubmission guidelines. Include any supporting documentation that addresses the denial reason.

Common RARC Pairings

The RARC code tells you exactly what triggered the CO-109:

How to Prevent CO-109

• Verify patient insurance eligibility and payer information before claim submission
• Maintain current payer routing tables that map service types to the correct payer/MAC
• Confirm provider enrollment status with each payer before submitting claims
• Implement eligibility verification at patient registration to catch coverage changes
• Train billing staff on Medicare MAC jurisdictions and how to route claims correctly

Also Filed As

The same CARC 109 may appear with different Group Codes:

Related Denial Codes