Mont. Code Ann. § 15-8-102

The county commissioners of each county shall provide existing office space in the county courthouse or other county building for use by the department's staff, if space is reasonably available. A county may charge the department a rate that does not exceed the rental rate that the department of administration charges state agencies for space in state buildings. If space is not reasonably available in the courthouse or other county building, the department may contract for the procurement of suitable space. For purposes of this section, "county building" includes a city-county building or a building maintained by a consolidated government.