Idaho Code § 31-3101
The salaries of county officers as full compensation for their services must be paid monthly from the county treasury, upon the warrants of the county auditor, and it shall not be necessary for the board of commissioners to allow or audit the claims for such salaries when the salaries of such officers are fixed by law or have been fixed or approved by action of the board of commissioners. All actual and necessary expenses incurred by any county officer or deputy in the performance of his official duty shall be a legal charge against the county, and shall be certified by receipts to the county auditor. The county auditor shall then issue a county warrant in the amount so certified, payable to the officer or deputy submitting the certification, and the warrant paid shall be charged against said officer's budget. When any such officer or deputy shall use his private car as a means of travel in the performance of his official duty the actual and necessary expense of the use of such car shall be determined by the county commissioners of each county and allowance made therefor at a rate for each mile driven shall be applied uniformly to each officer or deputy in that county and such allowance shall be the full amount allowable for travel expense when such car is used. All fees which may come into his hands from whatever source shall be turned into the county treasury daily, weekly, monthly, or quarterly as determined by the county commissioners. He shall, at least quarterly, file with the clerk of the board of county commissioners, a sworn statement, accompanied by proper vouchers, showing all fees received, which must be audited by the board as other accounts.
Idaho Code § 31-3101