If a taxable vehicle is registered in the name of both the owner and another person, the owner is liable for the tax. This rule also applies to dual registration of a leased vehicle.
Any vehicle operated under a dealer’s tag, license, or permit is considered registered in the name of the dealer.Used vehicle
If you acquire and register or are required to register a used taxable vehicle in your name during the tax period, you must keep as part of your records proof showing whether there was a use of the vehicle or a suspension of the tax during the period before the vehicle was registered in your name. The evidence may be a written statement signed and dated by the person (or dealer) from whom you purchased the vehicle.
If you acquire a vehicle and use it on the public highways in any month other than July, you are liable for the tax for the prorated tax period. You must file Form 2290 and pay the tax by the last day of the month after the month you use the vehicle.
If there is an unpaid tax liability for the months before you acquire and use the vehicle during the tax period, you are liable for the total tax for the entire period, to the extent not paid. In that case, you must file Form 2290 and pay the tax by the last day of the month after the month notification is received from the IRS that the tax has not been paid in full.