What is a MAC?

MAC stands for Medicare Administrative Contractor. It's a company that CMS has contracted to run the day-to-day operations of traditional Medicare in a given region. For the most part, the location in which you operate determines your MAC.

What's my MAC?

For Medicare Parts A + B, your MAC is based on the state in which you practice and the state in which you're enrolled with Medicare:

MAC	States / territories
CGS Administrators	KY, OH
First Coast Service Options (FCSO)	FL, PR, USVI
National Government Services (NGS)	CT, IL, MA, ME, MN, NH, NY, RI, VT, WI
Noridian	AK, AZ, CA, HI, ID, MT, ND, NV, OR, SD, UT, WA, WY, plus Guam, American Samoa, Northern Mariana Islands
Novitas	AR, CO, DC, DE, LA, MD, MS, NJ, NM, OK, PA, TX
Palmetto GBA	AL, GA, NC, SC, TN, VA, WV
WPS Health Solutions	IA, IN, KS, MI, MO, NE