Requirements
All carriers regulated by the UTC must obtain a United States Department of Transportation (DOT) number, even if you only operate within Washington State.
If you already operate in interstate commerce and have a DOT number, you do not need to do anything.
You may apply for a DOT number online at the Federal Motor Carrier Safety Administration (FMCSA) web site.
Even if the FMCSA web site indicates you don’t need a DOT number, Washington law requires a DOT number for intrastate operations.
To register by mail, download the Application for USDOT Number, Form MCS-150, from the FMCSA website.
If you have any other questions about your need for a DOT number or how to apply for one, you may call the Washington State Patrol at (360) 596-3810.