Mont. Code Ann. § 3-5-215

A district court judge of a judicial district composed of more than one county who, for the purpose of holding court and disposing of judicial business, goes to a county of that judicial district other than the county in which the judge resides and holds court or transacts judicial business must be paid the actual and necessary travel expenses, as defined and provided in 2-18-501 through 2-18-503, incurred on account of the business from the time the judge leaves the judge's place of residence until the judge returns to the place of residence.