Mont. Code Ann. § 16-1-401

(1) Except as provided in subsection (3), the department shall collect at the time of the sale and delivery of any liquor as authorized under any provision of the laws of the state of Montana an excise tax at a rate that is the percent of the retail selling price determined in accordance with the following schedule based on all liquor sold and delivered in the state by a company that manufactured, distilled, rectified, bottled, or processed the liquor and sold the specified number of proof gallons of liquor nationwide in the calendar year preceding imposition of the tax pursuant to this section: