Also known as MC number, MC authority is an interstate operating authority and a unique identifier given by the FMCSA to transport companies operating across state lines. Once you apply for the MC authority, it takes about 21 days to become active. So before you hire a shipping company, it’s essential to ask for their MC authority to verify they’re licensed to offer that type of service. A transport company without MC authority should be a big red flag because it means they’re not qualified to offer the services or even recognized by the government.