The Medicare program is in the process of making a transition from Medicare Carriers to Medicare Administrative Contractors. Medicare Carriers oversee Part B for specific states.
Medicare Administrative Contractors (MACs) will eventually oversee both Parts A and B for all of the 15 jurisdictions CMS has designated.
MACs are in place in 6 of the 15 jurisdictions, which are indicated by jurisdiction number in the complete list of Carriers (link below).
We will keep the list updated as assignments are made. However, in general the links provided for each of the states in transition from Medicare Carrier to MAC will link to the correct site, even if the entity has changed.
State Medicare Carriers, updated April 2009.