A Medicare Administrative Contractor (MAC) is a private health care insurer that has been awarded a geographic jurisdiction to process Medicare medical claims for Medicare Fee-For-Service (FFS) beneficiaries. CMS relies on a network of MACs to serve as the primary operational contact between the Medicare FFS program and the health care providers enrolled in the program. MACs are multi-state, regional contractors responsible for administering both Medicare Part A and Medicare Part B claims.
Take a look at the map above to find out who the Medicare Part A/B MAC is in your state.