Idaho Code § 31-1508
The board must not transfer any money from one fund to another nor in any manner divert the money in any fund to other uses, except in cases expressly provided and permitted by law: provided, that when any money shall have been assessed and collected in any of the counties of this state, and the same set apart as a separate fund, for special purpose, and from any cause the money in said fund shall have become inoperative for the purpose for which said fund was created, it shall be lawful for the board of county commissioners in such cases to transfer the money in said fund to such fund as the board of county commissioners may deem best. No transfer of money from one (1) county fund to another county fund shall be made upon the books of the county auditor and county treasurer unless the same is so authorized and so ordered by resolution of the board entered upon the records of its proceedings and certified copies of such resolution filed in the office of the county auditor and county treasurer.
The board shall not make any preferred creditor, nor cause any warrant to be drawn payable out of its order except on the order of the district court in cases provided by law, and the county treasurer shall in all things observe these instructions.
Idaho Code § 31-1508