DOT's newly established Federal Motor Carrier Safety Administration now operates a website that allows you to apply for registration and to pay fines for violations of the federal motor carrier safety regulations. The FMCSA's website address is www/fmcsa.dot.gov.
In addition, the Office of Hazardous Materials Safety website allows customers to pay for Freedom of Information Act requests, assessments and civil penalties at http://diy.dot.gov/hazmat.
Also available is the National Highway Traffic Safety Administration at http://diy.dot.gov/nhtsa/
You can use a credit card to make payments in a secure environment with on-line validation through each website.