Mont. Code Ann. § 19-13-605

Each employer shall make its contribution on behalf of members through the city treasurer or other appropriate official from money available for this purpose. The employer shall pay as employer contributions 14.36% of the compensation paid to all of the employer's employees, except those properly excluded from membership. All contributions are payable monthly to the board, which shall, as soon as practicable after their receipt, deposit them in the pension trust fund.