Persons traveling on official business for the state or any of its Legislative, Executive, and Judicial Branches, departments, institutions, boards, bureaus, commissions, councils, committees, or other like agencies in privately owned vehicles shall receive an amount equal to the mileage rate allowed by the Internal Revenue Code for income tax deductions per mile in lieu of actual expenses for transportation. Reimbursement shall be made no later than 30 calendar days from the date the request for reimbursement is initially received by the appropriate authority. For purposes of this section, travel, excluding members of the Legislature, means a departure from the permanent place of employment.