The Prime Minister may appoint a person to act as the Secretary of a Department:
(a) if there is a vacancy in the office of Secretary, whether or not an appointment has previously been made to the office; or
(b) during any period, or during all periods, when the Secretary is absent from duty or from Australia or is, for any reason, unable to perform the duties of the office.
Note: For rules that apply to acting appointments, see section 33A of the Acts Interpretation Act 1901 .