Mont. Code Ann. § 7-2-2243

Members of the board of commissioners provided for under 7-2-2241 shall receive a compensation of not to exceed $25 per day for every day they are actually employed under the provisions of this part. All of which expenses, together with the reasonable expenses of stationery, postage, and incidental expenses, shall be borne in equal proportions by the counties affected by such division, including said new county. The amounts payable by each county shall be paid by the treasurers of the respective counties after the same shall have been presented to and allowed by the board of county commissioners as is provided by law for claims against any county.