What's a MAC

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What's a MAC and what do they do?

A Medicare Administrative Contractor (MAC) is a private health care insurer that has been awarded a geographic jurisdiction to process Medicare Part A and Part B (A/B) medical claims or Durable Medical Equipment (DME) 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.  MACs perform many activities including:

  • Process Medicare FFS claims
  • Make and account for Medicare FFS payments
  • Enroll providers in the Medicare FFS program
  • Handle provider reimbursement services and audit institutional provider cost reports
  • Handle redetermination requests (1st stage appeals process)
  • Respond to provider inquiries
  • Educate providers about Medicare FFS billing requirements
  • Establish local coverage determinations (LCD’s)
  • Review medical records for selected claims
  • Coordinate with CMS and other FFS contractors

Section 911 of the Medicare Prescription Drug Improvement, and Modernization Act (MMA) of 2003 directed CMS to replace the Part A Fiscal Intermediaries (FIs) and Part B carriers with MACs.  CMS procures all MAC contracts according to the Federal Acquisition Regulation.  Various elements of the Agency’s original strategy for implementing Section 911 of the MMA evolved over the years.  Learn more about the strategy in the Archives.  

Currently there are 12 A/B MACs and 4 DME MACs in the program that process Medicare FFS claims for nearly 54% of the total Medicare beneficiary population, approximately 35 million Medicare FFS beneficiaries.  In Fiscal Year 2022 (FY2022), the MACs served more than 1.1 million health care providers who are enrolled in the Medicare FFS program.  Collectively in FY2022, the MACs processed more than 1.1 billion Medicare FFS claims, comprised of approximately 202 million Part A claims and 957 million Part B claims, and paid out approximately $422.5 billion in Medicare FFS benefits.  

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A/B MACs process Medicare Part A and Medicare Part B claims for a defined geographic area or “jurisdiction,” servicing institutional providers, physicians, practitioners, and suppliers.  Learn more about A/B MACs at Who are the MACs.  

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Home Health and Hospice Areas (HH+H)

There are four A/B MACs that process home health and hospice claims in addition to their typical Medicare Part A and Part B claims.  Please note that the four HH+H areas do not coincide with the jurisdictional areas covered by these four A/B MACs.  Learn more about HH+H areas and the MACs responsible for them at Who are the MACs.

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The DME MACs process Medicare Durable Medical Equipment, Orthotics, and Prosthetics (DMEPOS) claims for a defined geographic area or "jurisdiction", servicing suppliers of DMEPOS.  Learn more about DME MACs at Who are the MACs.

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Relationships between MACs and Functional Contractors

MACs work with multiple functional contractors to administer the full FFS operational environment.  Learn more about the relationships between the MACs and the functional contractors by viewing the diagram of MACs: The Hub of the Medicare FFS Program (PDF) and reading about what the functional contractors do at Functional Contractors Overview (PDF).

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Page Last Modified:
03/16/2023 03:26 PM