The Division of Motor Vehicles Motor Carrier Services Section of the Wisconsin Department of Transportation is sending out a warning to carriers to keep an eye out for scam letters. The letters are telling trucking companies to pay for their DOT biennial update. A good sign that it is a not a scam letter or email is to make sure the website ends in .GOV. Carriers must file their USDOT numbers every two years, but it can be done for free at the FMCSA website.