Your Medicare Administrative Contractor (MAC)
Checked against the current rules on September 24, 2026.
A Medicare Administrative Contractor (MAC) is the private company under contract with CMS that processes your Original Medicare claims and decides your Level 1 redetermination request — organized by geographic jurisdiction, not by claim type.
Unlike the QICs, this page deliberately doesn't list which MAC covers which state.
Why no state-by-state MAC table
MAC jurisdiction assignments are actively re-competing in 2026 — CMS periodically re-bids these contracts, and a contractor covering a state today can be replaced within the year. CMS's own source of truth is an interactive map, not a document that reduces cleanly to a static list.
A wrong guess here would send a family to the wrong contractor entirely — worse than no answer at all. Rather than publish a table with a real chance of being out of date by the time you read it, this page points you to the one source that's always correct for your specific claim.
The reliable source: your own notice
Your Medicare Summary Notice and your MAC's own redetermination decision both print the contractor's name and mailing address directly on the document — that's specific to your actual claim, not a state-level guess, and it's always current.
Find your Medicare Administrative Contractor (MAC): https://www.cms.gov/medicare/coding-billing/fee-schedules/mac-info — CMS's own official lookup, useful if you don't have a recent notice in hand.
What a MAC actually decides
Your MAC redetermines your denied claim at Level 1 — a different reviewer than whoever processed the original claim, but the same contractor. It has 60 calendar days to decide once it receives your timely request, extended by up to 14 more days each time you submit new evidence after filing.42 CFR 405.950
Sending your redetermination request to the right address matters — a request sent to the wrong contractor's address can genuinely delay processing, which is exactly why the notice's own printed address is worth double-checking before you mail anything.
The one MAC fact independently confirmed
Florida is Jurisdiction N, served by First Coast Service Options — independently confirmed with real confidence. It isn't packaged as a standalone directory entry here, since a single hardcoded state when every other state points to "check your own notice" would misleadingly suggest the other 49 were checked with the same confidence.
What happens after redetermination
If your MAC's redetermination is unfavorable, the next level is a reconsideration by a QIC — a genuinely different, independent organization, not another department at the same MAC. See the QIC pages in this same family for real, verified contact information.
Questions people ask
- How do I find my MAC if I don't have a recent notice?
- Use CMS's own MAC lookup tool, linked above — it's the same official source CMS itself points to, kept current as contracts change.
- Does it matter which MAC processes my claim?
- The coverage rules a MAC applies are the same regardless of which company holds the contract for your state — what matters is sending your redetermination request to the correct current address, which your own notice already gives you.
Sources — last checked September 24, 2026
- 42 CFR 405.950as of September 24, 2026
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By CaseWhy Appeals editorial. See how this content is produced. Not legal advice. Not affiliated with or endorsed by Medicare, CMS, or any health plan. A product of CaseWhy LLC.
