The liability for the tax levied and imposed by this chapter shall arise and accrue at the time and place where any motor vehicle owned or operated by any carrier specified in this chapter shall go or enter upon any highway of this state. The amount of tax for which any owner or operator is liable shall be paid and the tax liability of such owner or operator shall be discharged by one (1) of the following methods:
For the purposes of paragraph (a) of this section, the quantity of fuel needed to operate a motor vehicle in this state shall be determined by dividing the average miles per gallon allowed for each type of classification of motor vehicle into the number of miles such vehicle is deemed to have traveled in the state.
There shall be no credit allowed or adjustment made for any fuel consumed in auxiliary equipment when the fuel consumed by such equipment is supplied by the same fuel tank or tanks that supply fuel for the operation of the motor vehicle. Provided further that no credit shall be allowed or adjustments made for fuel used in power-take-off operations, loading or offloading or for idle time.
Miss. Code § 27-61-7