Your agency may pay only those expenses essential to the transaction of official business, which include:

(a) Transportation expenses as provided in part 301-10 of this chapter;

(b) Per diem expenses as provided in part 301-11 of this chapter;

(c) Miscellaneous expenses as provided in part 301-12 of this chapter; and

(d) Travel expenses of an employee with special needs as provided in part 301-13 of this chapter.