69-12-421. Annual fee for motor carriers. (1) Except as provided in subsection (2), in addition to all of the licenses, fees, or taxes imposed upon motor vehicles in this state and in consideration of the use of the public highways of this state, every motor carrier shall, at the time of the issuance of a certificate and annually thereafter, on or between October 1 and the following January 31, pay to the public service commission of Montana a fee set by rule of the commission for every motor vehicle operated by the carrier over or upon the public highways of this state.

(2) (a) A motor carrier engaged in seasonal operations only, where its operations do not extend continuously over a period of not to exceed 6 months in any calendar year, shall only be required to pay compensation and fees in a sum equal to one-half of the compensation and fees herein provided.

(b) The compensation and fees herein imposed shall not apply to motor vehicles maintained and used by a motor carrier as standby or emergency equipment. The commission shall have the power and it is hereby made its duty to determine what motor vehicles shall be classed as standby or emergency equipment.