Michigan Compiled Laws, Chapter 29. Fire Prevention § 29.474

(a) A motor carrier shall determine its percentage of transportation in this state by dividing the number of miles traveled in this state under the international registration plan during the previous year by the number of miles it traveled nationwide under the international registration plan. If a motor carrier operated only in this state, its percentage is 100%. If a motor carrier is not registered in the international registration plan, the motor carrier shall calculate the number of miles traveled using the method in the international registration plan. If a motor carrier operates more than 1 fleet under the international registration plan, the motor carrier may calculate each fleet's contribution to the motor carrier's total fee separately. A motor carrier who operated in another state under a reciprocal agreement with that state shall include the miles operated under the agreement as miles traveled in this state in calculating mileage under this section.

(b) A motor carrier shall determine its percentage of hazardous materials transportation using either of the following:

(c) A motor carrier shall select the midpoint of the 10% range that most closely approximates the motor carrier's calculation of its hazardous materials transportation business, under either option in subdivision (b).

(d) A motor carrier may use data from its most recent complete fiscal year or the most recent calendar year in calculating the percentage required under this section.