Medicare does not process your claims. About a dozen private contractors do, in defined geographic jurisdictions, and yours writes local coverage policy the next state over does not follow. The contractor decides your coverage rules, your redeterminations and your audits.
Providers talk about "billing Medicare" as though Medicare were a single desk. It is not. Medicare sets national rules and then contracts the actual work — processing, paying, and hearing the first level of appeal — to a set of private companies operating in defined geographic jurisdictions.
These are Medicare Administrative Contractors, and there are roughly a dozen covering the country. Novitas, Palmetto GBA, Noridian, WPS, National Government Services, CGS, First Coast. Your state belongs to exactly one of them for Part B.
Why the distinction is practical, not trivia
Three things follow from which contractor covers you.
They decide your appeal. A redetermination — the first level — is heard by the same contractor that denied the claim. Knowing who they are and how they read a particular policy is not administrative color; it is the substance of whether an appeal succeeds.
They write local coverage determinations. National coverage determinations set the floor, and local determinations fill the very large gaps between them. This is why identical care is covered in one state and denied in another with no change in national policy. If you have ever been told "that is covered in our other office," this is usually why.
Their policies travel across their jurisdiction. A contractor covers several states, so an appeal argument that works in one usually works in all of them. If you operate across state lines, knowing which of your locations share a contractor tells you where your existing knowledge transfers and where it does not.
What to do with this
Know your contractor by name. When a Medicare denial arrives, check whether a local coverage determination governs it before writing an appeal on clinical grounds — arguing medical necessity against an explicit local policy is a losing posture, and the winning argument is usually that the policy is satisfied rather than that it should not apply.
Learn your contractor’s materials
Each contractor publishes local coverage determinations, billing guidance and articles specific to its jurisdiction. That is where the answers live, and generic Medicare guidance frequently contradicts them.
Bookmark your contractor’s site rather than searching for Medicare rules generally.
Multi-state groups need multiple answers
A practice with locations in different jurisdictions has different coverage rules for the same service. Treating Medicare as a single national payer is the assumption that produces those denials.
Map each location to its contractor and check policies per jurisdiction for the services that matter.
Watch for jurisdiction changes
When a contract is re-awarded, submission details, portals and local policy can all change. The transition is announced but easy to miss, and the symptom is a sudden cluster of unexplained rejections.
Common questions
- What is a Medicare Administrative Contractor?
- A private company contracted by CMS to process Medicare claims, issue local coverage determinations, handle redeterminations and conduct reviews within a defined jurisdiction.
- How do I find my MAC?
- By geography — the jurisdiction covering your practice location. CMS publishes the jurisdiction map, and it changes occasionally when contracts are re-awarded.
- Why does my MAC matter?
- It writes the local coverage determinations that decide what is payable, processes your claims, and hears the first level of appeal.
- Can two practices have different Medicare rules?
- Yes, where no national determination exists. Different contractors reach different conclusions, so identical care can be covered on one side of a state line and not the other.
- Does my MAC change?
- Occasionally, when CMS re-awards a jurisdiction. It changes who you contact and which local policies apply, so it is worth noticing when it happens.
Denials Piling Up?
We handle the revenue cycle end to end — coding by certified coders, claim submission, denial management and appeals, and A/R follow-up, with six reported numbers every month.