Mont. Code Ann. § 27-18-406

Money, credits, or other property belonging to or due and owing to another, in the possession of or under the control of a public officer or board, including all officers or boards of a county, municipal corporation, and school district or state board or state government, may be attached or garnished while in possession or under control by making service, as provided in this part, upon the clerk of the county or presiding officer of the board of county commissioners, the city clerk or mayor of a municipal corporation, or the clerk of the board of school trustees or presiding officer of the board of trustees.