Please review the section on Do I need a DOT and MC #? If the answer is yes, the minimum level of insurance is as follows:
Vehicles with a seating capacity of less than 16 – $1.5m
Vehicles with a seating capacity of 16 or greater – $5m
Non-Hazmat – $750k
Hazmat – 1m or 5m dependent on quantity and type transported.
Check here for more info.