23.3.803 VEHICLE YEAR OF MANUFACTURE AND AGE
(1) All vehicles will be assigned a year of manufacture. If the year of manufacture cannot be determined from electronic records maintained on the system by the department or from information provided by the applicant at the time of original registration, the year of manufacture will be determined as follows:
(a) a rebuilt light vehicle, bus, heavy truck or truck tractor will be assigned the manufacture year of the vehicle body;
(b) a custom-built vehicle will be assigned the year stated on the manufacturer's certificate of origin or if the former is not available, the year of original registration;
(c) a glider kit will be assigned the year stated on the manufacturer's certificate of origin;
(d) a replica vehicle will be assigned the year of manufacture of the vehicle being replicated; and
(e) a homemade trailer will be assigned the year in which a vehicle identification number is assigned to the trailer by the department. If the trailer has previously been registered in another jurisdiction which has not designated a year of manufacture, the year of manufacture is deemed to be the year the vehicle was initially registered in the other jurisdiction. If the previous jurisdiction excluded the trailer from registration, the year of manufacture will be assigned based on a statement from the applicant made under penalty of law. No license plates or permits will be issued for a homemade trailer until a year of manufacture has been assigned by the department and the trailer has been inspected.
(2) The age of a vehicle is determined by subtracting the year of manufacture for the vehicle, as determined by the department, from the calendar year for which the tax or fee in lieu of tax is due, subject to the exceptions provided for in 61-3-522 , 61-3-523 , 61-3-527 and 61-3-530 , MCA for certain motor homes, travel trailers, campers, motorcycles, quadricycles or trailers, pole trailers or semi-trailers that have a declared weight of less than 26,000 pounds and that are not subject to proportional registration.