Medicare Administrative Contractor (MAC)
Medicare Administrative Contractor
CMS-contracted regional entity that processes Medicare claims, makes coverage decisions, conducts provider education, and handles first-level appeals.
1 min read · Last reviewed May 23, 2026
At a glance
- Category
- Payer
- Acronym for
- Medicare Administrative Contractor
- Primary sources
- 1
- Workspace handoff
- ask d3 →
Where this comes up
Front-office and billing both hit this term — eligibility before the visit, prior auth before the procedure, contract terms during fee-schedule negotiation, and credentialing whenever a new provider joins or a payer roster lapses. Misses here become denials downstream.
Full definition
What it is in practice
CMS MACs are split by jurisdiction. Each MAC publishes its own LCDs and articles, processes claims for its jurisdiction, and runs the Redetermination appeals stage.
How it shows up in your practice
Know your MAC. LCDs and bulletins published by your MAC have direct payment implications. Subscribe to MAC listservs.
Sources
- CMS — Medicare Administrative Contractorshttps://www.cms.gov/medicare/coding-billing/medicare-administrative-contractors-macs
Confirm MAC jurisdiction in Ask D3
Open ask d3 →Related terms
- PayerLCD (Local Coverage Determination)A MAC-published decision about whether a service is reasonable and necessary in its jurisdiction.
- PayerNCD (National Coverage Determination)A CMS-issued nationwide determination of whether Medicare will cover a particular service.
- Denials & AppealsRedeterminationThe first level of the Medicare claims appeal process, conducted by the MAC.
D3rx is a healthcare-billing and compliance research aid maintained by D3rx Inc. Articles are drafted by an LLM (Anthropic Claude) against primary HHS, OCR, CMS, eCFR, NIST, and state-regulator publications, and reviewed for restraint and source fidelity by the D3rx team.
Reviewer status: a named credentialed reviewer (CHC, CHPC, or healthcare attorney) is being engaged. Until that engagement is finalized, this page does not claim credentialed review.
Related across the archive
- GlossaryLCD (Local Coverage Determination)A MAC-published decision about whether a service is reasonable and necessary in its jurisdiction.
- GlossaryNCD (National Coverage Determination)A CMS-issued nationwide determination of whether Medicare will cover a particular service.
- GlossaryRedeterminationThe first level of the Medicare claims appeal process, conducted by the MAC.
- GlossaryCHIP (Children's Health Insurance Program)State-administered federal program providing health coverage to children in families with incomes too high for Medicaid but too low for private coverage.
- GlossaryFPL (Federal Poverty Level)Annual income thresholds published by HHS used to determine eligibility for federal programs.
- GlossaryMAC LCD ArticleA Local Coverage Article published by a MAC to provide billing, coding, or coverage clarification that does not rise to the formal LCD.
- GlossaryMedicaidJoint federal-state program providing health coverage to certain low-income individuals, families, pregnant women, elderly, and people with disabilities.
- ComplianceOIG LEIE Monthly Exclusion Screening: Process + Audit-Ready LogsMonthly OIG LEIE and SAM.gov exclusion screening for every workforce member and vendor: the workflow, the log fields auditors require, and the escalation path.
This glossary entry is a research aid for billing and compliance staff. It does not provide legal, medical, or financial advice and does not replace counsel. References cited link to primary sources at HHS, OCR, CMS, eCFR, NIST, and the relevant payer or industry body.