Home Denial Codes CO-126
Denial Code CO-126

Deductible (Updated for 2026)

Deductible

Quick Explanation

Denial code CO-126 indicates that the billed service, or a portion of it, was not paid by the insurance carrier because the amount was applied to the patient's annual out-of-pocket deductible. This means the financial responsibility for the designated amount shifts from the payer to the patient under the terms of their health plan. This is a standard contractual adjustment and requires the provider to bill the patient directly for the outstanding balance.

Common Causes for CO-126

Denials with code CO-126 typically happen for the following specific reasons:

How to Prevent CO-126 Denials

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

Appeal Letter Template for CO-126

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-126 - Deductible

Dear Appeals Department,

I am writing to appeal the denial of the above-referenced claim, which was denied with code CO-126: "Deductible".

We are appealing the application of the deductible (CO-126) to this claim. Under the Affordable Care Act (ACA) and CMS guidelines, qualifying preventive services must be covered at 100% by the plan without any patient cost-sharing, meaning they are exempt from the annual deductible. The service billed under CPT code [Insert CPT Code] was preventive in nature and should have been adjudicated as such. Alternatively, if this was a non-preventive service, our verified records indicate the patient's annual deductible had already been fully satisfied prior to this date of service. We respectfully request that you review the patient's accumulator history and reprocess this claim for appropriate payment.

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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