(1)  Except as provided in regulation 51 , a member to whom this Part applies must contribute to the PRB Fund as provided in this regulation.

(2)  A member's contributions must comprise a sum calculated at the rate of –

(a) in respect of his or her first 20 years' service as a member – 9% of the annual amount for the time being of his or her parliamentary salary; and

(b) in respect of any service after his or her first 20 years' service as a member – 9% of the annual amount for the time being of any part of his or her parliamentary salary that exceeds his or her basic salary.