Appeal — TEST-CLAIM-00068

Date: [Date of Submission]

Appeals and Grievances Department
Synthetic Humana
[Payer Address]

Re: Formal Appeal of Claim Denial — CO-18 Exact Duplicate
Claim Reference: TEST-CLAIM-00068
Service Date: 2026-04-19
Denied Amount: $918.81
Appeal Deadline: 2026-08-08

To Whom It May Concern:

On behalf of [Hospital/Provider Name], we submit this formal appeal contesting the denial issued by Synthetic Humana on 2026-06-09 for Claim TEST-CLAIM-00068. The claim was denied under remark code CO-18 (Exact Duplicate Claim/Service) for a partial amount of $918.81 of the $2,487.14 billed for services rendered on 2026-04-19, encompassing procedure codes CPT 24996, 95814, and 95316, with a primary diagnosis of ICD-10 S82.57. We respectfully assert that this denial is factually incorrect and request that Synthetic Humana reprocess and pay the denied amount of $918.81 in full.

**Basis for Appeal**

**I. The CO-18 Denial Is Not Supported by a True Exact Duplicate**

A CO-18 denial requires the payer to identify a specific, previously adjudicated claim that is identical in service date, procedure codes, and billed amount to the claim being denied. Our billing records, as reflected in the enclosed itemized claim submission records and hospital billing system audit trail, demonstrate that only a single claim was submitted for the services rendered on 2026-04-19 under the procedure codes listed above. We have found no evidence of a duplicate submission originating from our facility.

**II. The Partial Denial Amount Undermines the Duplicate Determination**

Critically, Synthetic Humana has denied only $918.81 of the $2,487.14 total billed — a partial amount that does not correspond to any single procedure line item consistent with an exact duplicate. Under the payer's own duplicate claim submission rule, a valid CO-18 denial must identify a previously adjudicated claim with a matching service date, identical procedure codes, and matching billed amount. The fact that only a portion of the claim was denied strongly suggests that Synthetic Humana cross-matched Claim TEST-CLAIM-00068 against a different, non-identical claim, or that a payer-side processing error resulted in erroneous duplicate flagging. Neither circumstance satisfies the criteria for a legitimate CO-18 denial.

**III. Supporting Documentation Confirms a Single, Distinct Submission**

The following enclosed documents collectively establish that this claim represents a single, unique submission for services actually rendered on 2026-04-19, and that no true duplicate exists:

- The enclosed itemized claim submission records identify the original submission date and unique claim reference number associated with Claim TEST-CLAIM-00068.
- The enclosed hospital billing system audit trail confirms the submission history and shows no secondary or duplicate filing for the same date of service and procedure codes.
- The enclosed service date documentation (procedure note and/or visit record for 2026-04-19) verifies that the services billed under CPT 24996, 95814, and 95316 were provided as a single encounter.
- The enclosed Explanation of Benefits and payer claim history report are requested to identify and confirm the specific previously adjudicated claim Synthetic Humana alleges as the duplicate; to date, no such corresponding claim reference has been provided in the denial correspondence.

We further note that, to date, Synthetic Humana has not provided documentation identifying the allegedly duplicate claim by claim number, adjudication date, or matching billed amount. Such identification is a prerequisite for a valid CO-18 determination and its absence further supports reversal of this denial.

**IV. Requested Remedy**

Based on the foregoing, we respectfully request that Synthetic Humana:

1. Reprocess Claim TEST-CLAIM-00068 in its entirety;
2. Reverse the CO-18 denial and issue payment of the denied amount of $918.81; and
3. Provide, if applicable, the specific claim number and adjudication details of the alleged prior duplicate claim for our records and reconciliation.

Should Synthetic Humana require additional documentation to complete its review, please contact [Hospital Contact Name and Phone Number] at your earliest convenience. We respectfully request a written determination prior to the appeal deadline of 2026-08-08.

Thank you for your prompt attention to this matter.

Respectfully,

[Authorized Signature]
[Name and Title]
[Hospital/Provider Name]
[Address]
[Phone Number]
[Date]

Enclosures:
1. Itemized claim submission records (submission date and claim reference number)
2. Hospital billing system audit trail
3. Service date documentation (procedure note/visit record for 2026-04-19)
4. EOB or payer claim history report
5. Denial correspondence from Synthetic Humana dated 2026-06-09