US · guidance
CMS Pub. 100-05, ch. 1, § 30.4
MSP CWF Process
The CWF holds all Medicare beneficiaries’ Part A and Part B data. All beneficiaries
have a master record in CWF. CMS uses the MSP Auxiliary file within CMS to identify
MSP occurrences in order to ensure accurate Coordination of Benefits. Currently in
Chapter 6 of the Medicare Secondary Payer Manual, the CWF process as it pertains to
MSP and Coordination of Benefits is explained. It gives A/B MACs and DME MACs an
idea of how to use the CWF when their role requires it and how it is used by CMS for
MSP activities.
History
(Rev. 11755, Issued:12-21-22, Effective: 01-23-23, Implementation: 01-23-23)
Provenance
- Source
- cms.gov
- Retrieved
- 2026-08-25
- Edition
- iom-2026-08-25
- Content hash
7e0abfdfd5cf43f10af9485f41bb5c54932cec468d7d57fe6d5b8ddb5cde3d0c
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