You must pay the state sales tax on any vehicle purchased outside Mississippi and on any casual sale of an automobile. The state sales tax rate is 5% and is based on the dealer’s selling price before subtracting any dealer’s discounts and trade-ins. Tax on a casual sale is based on the assessed value of the vehicle as determined by the most recent assessment schedule. If you purchase a vehicle out-of-state and it is first tagged in Mississippi, you will not be given any tax credit for any sales tax paid to the other state.