Modify the Application Logic to Conditionally Retain the Medicare Carrier System (MCS) Medicare Secondary Payer (MSP) Claim Trailer Based on Specific Common Working File (CWF) Error Codes, Dispositions, and Override Values
The purpose of this Change Request (CR) is to re-design the MCS processing of the CWF MSP response to ensure that claims denied by receipt of a CWF MSP error are re-transmitted with the correct MSP information. This provides MACs with the ability to remove the CWF MSP trailer information when discrepancies are found in the returned CWF information. The system will prevent the distribution of false data to downstream systems by preventing the incorrect overlay of the 03 trailer.
Issued by: Centers for Medicare & Medicaid Services (CMS)
Issue Date: July 23, 2026
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