(1) If a member acts as a Minister for a continuous period of 30 days or more, for the whole of the period the member acts, the member is to be paid any additional salary at the rate for the time being applicable to the office of the Minister.
(2) Subsection (3) applies if—
(a) a Minister (the first Minister) acts in another Minister's office for a continuous period of 30 days or more; and
(b) a higher additional salary under section 42 is payable for the other Minister's office.
(3) For the whole of the period the first Minister acts, the first Minister is to be paid the higher additional salary at the rate for the time being applicable to the other Minister's office.