13.—(1) A person other than an employee of an admission body who is eligible to be an active member of the Scheme on the day his employment begins becomes an active member on that day unless he notifies his employer in writing before his employment begins that he does not wish to become a member on that date.
(2) A person who applies to become a member after the date he would otherwise become a member under paragraph (1) becomes a member on the first day of the first payment period following the application.
(3) Subject to paragraph (5), a person other than an employee of an admission body who only becomes eligible to be a member of the Scheme on a date after his employment begins becomes an active member on that date unless he notifies his employer in writing before that date that he does not wish to become a member on that date.
(4) A person who applies to become a member after the date he would otherwise become a member under paragraph (3) becomes a member on the first day of the first payment period following the application.
(5) A person referred to in paragraph (3) who is employed by a body listed in Part 1 of Schedule 2 may be an active member from the date that his employment began if he applies to be so and pays contributions in respect of that earlier period at the appropriate contribution rate as provided in regulation 3 of the Benefits Regulations.
(6) An eligible employee of an admission body who wishes to become an active member in that employment must apply in writing to his employer and
(a)if he applies before that employment begins, he becomes a member when the employment begins; or
(b)if he applies after his employment begins, he becomes a member on the first day of the first payment period following the application.
(7) A former active member who is eligible for membership may reapply for membership of the Scheme and he becomes an active member on the first day of the first payment period following the application.
(8) In paragraphs (2), (4), (6) and (7), regulation 14(5) (ending of membership) and regulation 23(7) (payment of additional regular contributions), a payment period is a period of service to which the employee’s wages or salary payment relate.