28 CFR § 45.4 - Personal use of Government property.
(a) Employees may use Government property only for official business or as authorized by the Government. See 5 CFR 2635.101(b)(9), 2635.704(a). The following uses of Government office and library equipment and facilities are hereby authorized:
(1) Personal uses that involve only negligible expense (such as electricity, ink, small amounts of paper, and ordinary wear and tear); and
(2) Limited personal telephone/fax calls to locations within the office's commuting area, or that are charged to non-Government accounts.
(b) The foregoing authorization does not override any statutes, rules, or regulations governing the use of specific types of Government property (e.g. internal Departmental policies governing the use of electronic mail; and 41 CFR (FPMR) 101–35.201, governing the authorized use of long-distance telephone services), and may be revoked or limited at any time by any supervisor or component for any business reason.
(c) In using Government property, employees should be mindful of their responsibility to protect and conserve such property and to use official time in an honest effort to perform official duties. See 5 CFR 2635.101(b)(9), 2635.704(a), 2635.705(a).