Idaho Code § 67-2006: Travel expense — Vouchers.

On all vouchers submitted for travel expenses, there must appear a certificate signed by the head of the department for which the travel was performed, stating that the travel was performed under competent orders, the purpose for which it was undertaken, and that the same was necessary in the public service. The person submitting a voucher for travel expenses must sign thereon a certificate that the account is correct and just.