Mont. Code Ann. § 22-1-313
22-1-313 Existing tax-supported libraries -- notification -- exemption from county taxes
22-1-313 . Existing tax-supported libraries -- notification -- exemption from county taxes. After the establishment of a county free library as provided in this part, the governing body of any city which has an existing tax-supported public library may notify the board of county commissioners that such city does not desire to be a part of the county library system. Such notification shall exempt the property in such city from liability for taxes for county library purposes.