Glossary · Compliance

Medicare Administrative Contractor (MAC)

A Medicare Administrative Contractor (MAC) is a private insurance company under contract with CMS to process and pay Medicare Part A and Part B fee-for-service claims within an assigned geographic jurisdiction. MACs are the primary point of contact for providers on coverage policies, claims adjudication, and local coverage determinations.

Verified May 8, 2026 · 7 sources ↓

Drawn from CMSEcfrMedicare Prescription

Definition

Source · Editorial summary grounded in 7 cited references ↓

Before 2003, Medicare claims were handled by separate Part A Fiscal Intermediaries and Part B carriers. Section 911 of the Medicare Prescription Drug, Improvement, and Modernization Act of 2003 directed CMS to consolidate those functions into unified A/B Medicare Administrative Contractors, procured under the Federal Acquisition Regulation. Today, a small number of regional MACs collectively cover all 50 states, processing claims for physicians, hospitals, outpatient facilities, home health agencies, hospices, and durable medical equipment suppliers.

Each MAC carries broad operational authority within its jurisdiction. Core functions include adjudicating claims against national and local coverage rules, issuing Local Coverage Determinations (LCDs) and Local Coverage Articles, conducting medical review, educating providers on billing and coding compliance, and managing provider enrollment. MACs also analyze billing patterns for aberrancies and develop outreach programs aimed at reducing improper payments—activities mandated by CMS under the Provider Outreach and Education framework.

For orthopedic practices, the MAC is the frontline arbiter of whether a claim is paid, pended, or denied. It enforces NCCI edits, applies ICD-10-CM diagnosis-date requirements, and issues the LCDs that define medical necessity criteria for procedures ranging from total joint replacement to nerve conduction studies. Knowing which MAC covers your practice's geographic location—and monitoring that MAC's active LCDs and billing articles—is a non-negotiable part of revenue cycle management.

Why it matters

The MAC that covers your jurisdiction determines which Local Coverage Determinations apply to your orthopedic claims. An LCD issued by one MAC does not automatically govern a practice in a different jurisdiction, so a total knee arthroplasty claim that sails through in one region can face a medical-necessity denial in another if the operative note does not satisfy the local MAC's specific documentation criteria. MACs also conduct prepayment and post-payment medical review; a pattern of claims that deviates from the MAC's published billing guidelines can trigger a Targeted Probe and Educate (TPE) review, extrapolated overpayment demands, or referral to a Recovery Auditor—all of which carry significant financial and administrative costs for the practice.

Common mistakes

Where people most often go wrong with this concept.

Source · Editorial brief grounded in cited references ↓

Applying a MAC's LCD from a neighboring jurisdiction instead of the MAC that actually holds the contract for your practice's state—coverage criteria frequently differ between MACs.
Failing to check the MAC's website for jurisdiction-specific billing articles when a national LCD exists; the billing article often contains additional documentation requirements that the LCD body does not spell out.
Ignoring MAC-issued provider education bulletins about claim submission errors, which are later used as evidence of 'notice' during a medical review or audit.
Submitting ICD-10-CM diagnosis codes based on the date the claim is prepared rather than the date of service—MACs are required to edit claims on a date-of-service basis per Medicare Claims Processing Manual Chapter 23.
Not updating the practice's MAC assignment after a merger, acquisition, or relocation; provider enrollment with the wrong MAC causes systematic claim denials.
Treating all MACs as interchangeable for modifier and bilateral-procedure rules; while NCCI edits are national, MACs retain discretion in how they handle reopening requests for bilateral coding errors (e.g., modifier 50 vs. anatomic modifier pairs).

Related codes

Codes commonly involved when this concept appears in practice.

Modifiers

50 Bilateral procedure 59 Distinct procedural service

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 7 cited references ↓

01How do I find out which MAC processes claims for my orthopedic practice?

CMS publishes a MAC jurisdiction map on its website. Your practice's state and the type of benefit (Part A facility, Part B professional, or DME) determine which MAC holds your contract. Your billing system's payer ID list should reflect the correct MAC, but verify directly on the CMS MAC jurisdiction page whenever your practice changes locations or expands to a new state.

02Does a Local Coverage Determination from one MAC apply to my practice in a different state?

No. LCDs are jurisdiction-specific. Even if a neighboring MAC has issued an LCD covering a procedure, that document has no binding authority over claims submitted to a different MAC. Always retrieve LCDs directly from the MAC assigned to your practice's jurisdiction via the Medicare Coverage Database.

03Can a MAC deny a claim that meets a National Coverage Determination?

Generally, a MAC cannot impose additional restrictions that conflict with an NCD. However, when an NCD is silent on a particular service or indication, the MAC can issue an LCD to fill the gap, and that LCD can impose requirements beyond what the NCD addresses. Always check both levels of coverage policy.

04What triggers a Targeted Probe and Educate review by the MAC?

MACs analyze billing pattern data and claims error rates to identify providers whose coding deviates significantly from peers. High error rates on prepayment review, patterns flagged in CERT data, or complaints can all initiate a TPE review. Completing MAC-issued education is the primary way to exit the TPE process without escalation to a full post-payment audit.

05What is the difference between a MAC and a Recovery Auditor (RAC)?

A MAC processes claims and conducts routine medical review as part of day-to-day claims administration. A RAC is a separate CMS contractor that performs retrospective post-payment audits specifically designed to identify and recover improper payments. A MAC medical review finding can, however, be a referral source to a RAC or other program integrity contractor.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

01
cms.gov
https://www.cms.gov/medicare/coding-billing/medicare-administrative-contractors-macs
02
cms.gov
https://www.cms.gov/medicare/coding-billing/medicare-administrative-contractors-macs/resources-macs
03
ecfr.gov
https://www.ecfr.gov/current/title-42/chapter-IV/subchapter-B/part-421
04
cms.gov
https://www.cms.gov/regulations-and-guidance/guidance/manuals/downloads/com109c06.pdf
05
cms.gov
https://www.cms.gov/regulations-and-guidance/guidance/manuals/downloads/clm104c23.pdf
06
cms.gov
https://www.cms.gov/medicare/coding-billing/icd-10-codes
07Medicare Prescription Drug, Improvement, and Modernization Act of 2003, Section 911 (Pub. L. 108-173)

Mira AI Scribe

When Mira generates or reviews an orthopedic encounter note, it cross-references the billing entity's assigned MAC jurisdiction to surface the applicable Local Coverage Determinations and billing articles before the claim is finalized. Specifically, Mira flags whether the documentation satisfies that MAC's medical-necessity language—for example, conservative-treatment duration requirements prior to joint arthroplasty, or functional-limitation language required for orthotic or DME orders. If a diagnosis code is appended after the date of service, Mira alerts the coder, because MACs are required to edit on the actual date-of-service basis. For bilateral procedures, Mira checks whether the MAC's current guidance supports modifier 50 on a single line or requires separate lines with anatomic modifiers, reducing the risk of a denial that would require a reopening request. Mira also surfaces active MAC-issued provider education bulletins relevant to the procedure being coded, so coders can proactively correct common errors the MAC has already identified as targets for medical review.

See Mira's approach

A Local Coverage Determination (LCD) is a regional Medicare policy issued by a Medicare Administrative Contractor (MAC) that defines when a specific service, procedure, or supply is considered reasonable and medically necessary within that contractor's jurisdiction.

National Coverage Determination (NCD) Compliance

A National Coverage Determination (NCD) is a formal, evidence-based ruling issued by CMS that establishes whether Medicare will cover a specific item or service across all Medicare contractors nationwide. NCDs are binding on every Medicare Administrative Contractor and supersede any conflicting local policy.

Targeted Probe and Educate (TPE) Compliance

Targeted Probe and Educate (TPE) is a CMS Medicare audit program in which a Medicare Administrative Contractor (MAC) reviews 20–40 of a provider's claims per round—up to three rounds—and pairs findings with one-on-one education to reduce billing errors and future denials.

Advance Beneficiary Notice (ABN) Billing

An Advance Beneficiary Notice of Noncoverage (ABN) is a written notice providers and suppliers must deliver to Original Medicare (Part B) beneficiaries before furnishing an item or service that Medicare is expected to deny, transferring potential financial liability to the patient when properly executed.