Miss. Code Ann. § 25-1-79

It shall be unlawful for any officer, employee or other person whatsoever to use or permit or authorize the use of any automobile or any other motor vehicle owned by the State of Mississippi or any department, agency or institution thereof for any purpose other than upon the official business of the State of Mississippi or any agency, department or institution thereof. Further, it shall be unlawful for any such officer or employee to be paid or to receive any sums whatsoever for travel expense until the expenses for which payment is made, and each item thereof, have been actually incurred by such officer or employee, and then only upon the presentation of an itemized expense account which shall be approved in writing by the head of the department, agency or institution on whose behalf such travel is performed. However, it is expressly provided that any such officer or employee traveling on business for and in behalf of the State of Mississippi may, strictly in the discretion of an agency, institution or department head, receive in advance from state funds for the purpose of such travel expense a sum to be specified by such aforementioned superior. Further, strict account of any sum so advanced must be kept in accord with Section 25-1-81 .