Section 13-204. Reduction of contributions by members

The  mayor,  by
  executive order adopted prior to the first day of June, nineteen hundred
  sixty-three, may direct that  beginning  with  the  first  full  payroll
  period  following January first, nineteen hundred sixty-three and ending
  with the payroll period immediately prior to  that,  the  first  day  of
  which  is  nearest  to  June thirtieth, nineteen hundred sixty-four, the
  deductions from the semi-monthly pay, salary  or  compensation  of  each
  member  made  pursuant  to  the  provisions  of this subchapter shall be
  reduced  by  two  and  one-half  per  cent  of  such  pay,   salary   or
  compensation.  Such  executive  order  may  also provide for a method or
  procedure for the refunding or crediting to a member by the pension fund
  of the amount of the reduction in his or her deductions for  any  period
  prior  to  the  adoption  of such executive order. The benefits provided
  pursuant to this section shall apply only to members of the pension fund
  who are in active service in the police force on or after  the  date  of
  adoption of such executive order.