In general, companies that do the following are required to have interstate Operating Authority in addition to a DOT number:

• Transport passengers in interstate commerce (for a fee or other compensation, whether direct or indirect)
• Transport federally-regulated commodities owned by others or arranging for their transport, (for a fee or other compensation, in interstate commerce)

FMCSA operating authority is often identified as an "MC," "FF," or "MX" number, depending on the type of authority that is granted. Unlike the USDOT Number application process, a company may need to obtain multiple operating authorities to support its planned business operations. Operating Authority dictates the type of operation a company may run and the cargo it may carry.