45 C.F.R. § 73.203 – Use of Government funds.

(a) An employee must not:
1. (1) Improperly use official travel;
2. (2) Improperly use payroll and other vouchers and documents on which Government payments are based;
3. (3) Take or fail to account for funds with which the employee is entrusted in the employee's official position; or
4. (4) Take other Government funds for personal use.
  Violations of these prohibitions carry criminal penalties.
(b) In addition, employees must avoid wasteful actions or behavior in the performance of their assigned duties.