FMCSA has proposed no longer assigning MC Numbers. Consistent with statutory requirements, the USDOT Number would become the sole identifier for all FMCSA registrants. Individual registrations held by a distinct employer or person would be identified by unique suffixes within FMCSA’s systems, as required by MAP-21. This change is under consideration and will be available to comment on in a Notice of Proposed Rulemaking. It will not go into effect with the first release of the new registration system. See the attached examples on how the suffixes will be added to USDOT Numbers. Learn More.