Mont. Code § 7-21-2113
Every person who commences or carries on a business, trade, profession, or calling, for the transaction or carrying on of which a license is required by the provisions of any of the license laws of Montana, without taking out or procuring such license is guilty of a misdemeanor and shall, unless specific punishment is prescribed by some other law of this state, be punishable as in the case of other misdemeanors and, in addition thereto, shall be liable to a penalty of 10% of the amount of said license. This penalty must be added to the amount of said license and collected by the county treasurer at the time of the collection of the license, but the payment of said penalty shall in no event relieve any person from prosecution for such misdemeanor.
§ 7-21-2113, MCA