Quick Explanation
Denial code CO-35 occurs when there is a mismatch between the patient-to-subscriber relationship reported on the claim and the payer's eligibility database. It indicates that the claim was submitted designating the patient as a dependent or spouse, but the insurance carrier's records show that the patient is actually the primary policyholder (subscriber) themselves. To resolve this, the relationship code must be updated to indicate the patient and subscriber are the same individual.
Common Causes for CO-35
Denials with code CO-35 typically happen for the following specific reasons:
- An incorrect patient relationship code (such as 'Spouse' or 'Child' instead of 'Self') was entered in Box 6 of the CMS-1500 form or the electronic equivalent.
- Data entry errors during the patient registration process where the primary subscriber's details were swapped with a dependent's details.
- Outdated insurance information in the practice management system, such as a patient who recently aged out of a parent's plan and established their own policy but was billed under the old family hierarchy.
- Electronic data interchange (EDI) mapping issues where Loop 2000C (Patient Info) was unnecessarily populated when the patient is the subscriber, which should only utilize Loop 2000D.
How to Prevent CO-35 Denials
To avoid receiving this denial in the future, implement these specific checks:
- Utilize real-time eligibility (RTE) verification software at check-in to instantly verify the patient's exact relationship status as recorded by the payer.
- Implement claim scrubber rules to flag and hold any claims where the patient's name matches the subscriber's name but the relationship code is not set to 'Self' (Code 18).
- Train front-desk and intake staff to carefully distinguish between the policyholder and dependents during the insurance verification and card-scanning process.
- Establish a standard workflow to ask patients if they are the primary cardholder or if they are covered under another family member's plan during every visit.
Appeal Letter Template for CO-35
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-35 - The subscriber and the patient are the same
Dear Appeals Department,
I am writing to appeal the denial of the above-referenced claim, which was denied with code CO-35: "The subscriber and the patient are the same".
We are writing to appeal the denial of this claim under code CO-35. Upon comprehensive review of our active enrollment records and the patient's insurance card, we have confirmed that the patient is indeed the primary subscriber for this policy. The initial submission contained an administrative discrepancy in the patient relationship field (Box 6 / Loop 2000C), which incorrectly designated the patient under a non-self relationship. Pursuant to NUCC and CMS-1500 claim filing instructions, we have updated the relationship status to reflect 'Self' (Code 18) to align perfectly with your active subscriber files. We request that you update your records, reprocess this corrected claim, and remit payment accordingly.
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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