(a) The comptroller shall adopt rules governing the use of petty cash accounts established under this subchapter for advancing travel expense money to state officers and employees.
(b) The rules must:
(1) prohibit the use of a petty cash account to advance more than projected travel expenses to a state officer or employee;
(2) prohibit a state agency from using a petty cash account to advance travel expense money to a prospective state officer or employee;
(3) require a final accounting after a state officer or employee has incurred travel expenses; and
(4) prohibit a state agency from using a petty cash account for any purpose other than advancing travel expense money to a state officer or employee.

(c) In this section, “final accounting” means a reimbursement from or additional payment to a state officer or employee so that the net amount received by the officer or employee equals the actual travel expenses incurred by the officer or employee.