Miss. Code § 27-61-5
There is hereby levied and imposed, a privilege tax as reasonable compensation for the use of the highways of this state, in addition to all other taxes which may be levied for such purpose, as follows: upon each owner or operator of a common carrier by motor vehicle, contract carrier by motor vehicle, private commercial carrier of property by motor vehicle, common carriers of passengers, contract carriers of passengers, private carrier of passengers by motor vehicle, and private carrier of property, when any of such carriers operate a motor vehicle or motor vehicles that cross the boundary line of the State of Mississippi, a privilege tax equal to and computed at the prevailing excise tax rates for gasoline, special fuel, diesel fuel and compressed gas for highway use on all such fuel used in operating any motor vehicle in this state. The operator of any motor vehicle or motor vehicles which are so equipped that more than one (1) kind of motor fuel can be used shall be liable for the tax at the highest prevailing tax rate of the kinds of motor fuel so used within this state, with no credit allowed for the purchase of fuel with the lesser tax rate.
Miss. Code § 27-61-5