Mont. Code Ann. § 61-3-302

(1) (a) A resident of the state of Montana who owns a motor vehicle, trailer, semitrailer, or pole trailer may not operate the motor vehicle, trailer, semitrailer, or pole trailer with license plates issued by any other state than Montana.

(b) A person who has resided in Montana for more than 60 consecutive days is considered to be a resident for the purpose of vehicle titling and registration laws, and a motor vehicle, trailer, semitrailer, or pole trailer owned by the person must be titled and registered under the laws of Montana prior to operation in this state after the 60-day period.

(b) (i) A person who has resided in Montana for more than 60 consecutive days is considered to be a resident for the purpose of vehicle titling and registration laws, and a motor vehicle, trailer, semitrailer, or pole trailer owned by the person must be titled and registered under the laws of Montana prior to operation in this state after the 60-day period.

(ii) A person serving or retired from serving aboard the USS Montana is considered, at the election of the person, a resident for the purpose of motor vehicle titling and registration laws and may apply for a USS Montana specialty license plate pursuant to 61-3-479(1)(a)(ii). Residency is not conferred for any other purpose.

(2) A motor vehicle, trailer, semitrailer, or pole trailer driven or moved upon a highway in this state and owned by a nonresident of this state is exempt from registration under this chapter if:

(a) the vehicle is properly registered in and displays valid license plates of the jurisdiction in which the nonresident owner resides; and

(b) (i) the vehicle is not used for the transportation of persons or property for hire, compensation, or profit;

(ii) the nonresident owner is not employed or engaged in a commercial or business enterprise in this state; or

(iii) the vehicle is used for the exclusive purpose of filming motion pictures or television commercials and does not remain in the state for a period in excess of 180 consecutive days in a calendar year.

(3) A motor vehicle, trailer, semitrailer, or pole trailer that is owned by a manufacturer, a dealer, a wholesaler, or an auto auction and that is held for sale is exempt from registration under this part even though the motor vehicle, trailer, semitrailer, or pole trailer is incidentally moved on the highway and is used for purposes of testing or demonstration or is used by a manufacturer solely for testing.

(4) A junk vehicle, as defined in Title 75, chapter 10, part 5, being driven to an auto wrecking graveyard for disposal is exempt from the provisions of this chapter.

Residents operating motor vehicles under licenses issued by any state other than Montana forbidden – vehicles exempt from registration – exceptions