Mont. Code § 15-51-101
In addition to the license tax now provided by law, each person or other organization now engaged in the generation, manufacture, or production of electricity and electrical energy in the state of Montana, either through water power or by any other means, for barter, sale, or exchange (and hereinafter referred to as the "producer") shall on or before the 30th day after each calendar quarter, quarterly periods ending March 31, June 30, September 30, and December 31, render a statement to the department of revenue showing the gross amount, except for actual and necessary plant use, required to produce the energy of electricity and electrical energy produced, manufactured, or generated during the preceding calendar quarter without any deduction and shall pay a license tax thereon in the sum of $.0002 per kilowatt hour on all such electricity and electrical energy generated, manufactured, or produced, measured at the place of production and as shown on the statement required in the manner and within the time hereinafter provided.
§ 15-51-101, MCA