The excise is assessed to the registered owner of the vehicle by the city or town where the vehicle is customarily kept, as shown on the owner's application for registration to the Registry of Motor Vehicles (Form RMV-1). As a general rule, a vehicle is customarily kept in the city or town where the owner resides or has a principal place of business. If a vehicle is customarily garaged outside Massachusetts, the Commonwealth assesses the excise. G.L. c. 60A, sect. 2.