Home Denial Codes CO-124
Denial Code CO-124

Tertiary payor amount (Updated for 2026)

Tertiary payor amount

Quick Explanation

Denial code CO-124 occurs in multi-payer coordination of benefits (COB) scenarios where the current payer requires the payment, adjustment, or adjudication details from the tertiary insurance provider to determine its financial liability. It typically indicates that the prior payer's Explanation of Benefits (EOB) or payment data was missing, incomplete, or incorrectly formatted during claim submission. Ensuring all prior payer transactions balance is necessary for the subsequent payer to process the claim.

Common Causes for CO-124

Denials with code CO-124 typically happen for the following specific reasons:

How to Prevent CO-124 Denials

To avoid receiving this denial in the future, implement these specific checks:

Appeal Letter Template for CO-124

If you believe this claim was denied incorrectly, you can use the following template to submit an appeal.

[Your Practice Header]
[Date]

[Payer Name]
[Appeals Department Address]

RE: Appeal for Claim [Claim Number]
Patient: [Patient Name]
ID: [Patient ID]
Date of Service: [Date]
Denial Code: CO-124 - Tertiary payor amount

Dear Appeals Department,

I am writing to appeal the denial of the above-referenced claim, which was denied with code CO-124: "Tertiary payor amount".

We are appealing the denial under code CO-124 (Tertiary payor amount) for the attached claim. In compliance with the Coordination of Benefits (COB) guidelines outlined by the Centers for Medicare & Medicaid Services (CMS) and standard industry practices, we have successfully submitted complete adjudication data from all prior payers. The enclosed documentation includes the original claim alongside the Explanations of Benefits (EOBs) from the primary, secondary, and tertiary insurers, clearly detailing all payments, contractual adjustments, and patient responsibility portions. Because all prior payer liabilities have been appropriately accounted for and balanced, we request that this claim be reprocessed and payment be issued in accordance with your contractual obligation as the subsequent payer.

Attached please find:
1. A copy of the original claim.
2. The relevant medical records supporting the service.
3. [Any other supporting documents].

We respectfully request that you reprocess this claim for payment.

Sincerely,

[Your Name]
[Title]
[Practice Name]
            

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