42 CFR § 421.401 - Definitions.

---
identifier: "/us/cfr/t42/s421.401"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "42 CFR § 421.401 - Definitions."
title_number: 42
title_name: "Public Health"
section_number: "421.401"
section_name: "Definitions."
chapter_name: "CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "B"
subchapter_name: "MEDICARE PROGRAM"
part_number: "421"
part_name: "MEDICARE CONTRACTING"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 1302 and 1395hh."
regulatory_source: "45 FR 42179, June 23, 1980, unless otherwise noted."
cfr_part: "421"
---


# 421.401 Definitions.

For purposes of this subpart—

*Appropriate MAC* means a MAC that has a contract under section 1874A of the Act to perform a particular Medicare administrative function in relation to:

(1) A particular individual entitled to benefits under Part A or enrolled under Part B, or both;

(2) A specific provider of services or supplier; or

(3) A class of providers of services or suppliers.

*Medicare Administrative Contractor* (MAC) means an agency, organization, or other person with a contract under section 1874A of the Act.