C6. An opted-out office holder who is either–
(a)a participating member; or
(b)not a member of the Parliament,
may apply to rejoin the Scheme as a participating office holder as from the date of commencement of a new period of tenure of a qualifying office (“the effective opt-in date”) by giving notice in writing to the Parliamentary corporation within a period of 12 months beginning with the effective opt-in date provided that he pays to the Parliamentary corporation within 28 days of its acceptance of his application, or within such longer period as it may determine, the sum certified by the Parliamentary corporation as being the amount which would have been deducted from his office holder’s salary under article D1 between the effective opt-in date and the first date thereafter when a deduction from that salary under article D1 is made.