Section 13-208. Extra service pension credit

Except  as  provided  in
  subdivisions a and b of section 13-206 of this subchapter:
    1. A member who shall have elected  to  contribute  on  the  basis  of
  retirement after twenty years of service, upon completing such period of
  service,  may continue in the service. In such event and upon retirement
  for service, there shall be added to his or her annual  service  pension
  one-sixtieth  of  the salary received at the date of retirement for each
  completed additional year of service, during which years such deductions
  shall have been made. Any such member upon completing twenty-five  years
  of  service,  shall  have  such  deductions made at the rate of five per
  cent, in which event and upon retirement for  service,  such  additional
  amounts also shall be added to his or her annual service pension for the
  years  during  which deductions shall have been made at the rate of five
  per cent.
    2. A member who shall have elected  to  contribute  on  the  basis  of
  retirement  after  twenty-five  years  of  service, upon completing such
  period of service, may continue in the  service.  In  such  event  there
  shall  be added to his or her annual service pension upon retirement for
  service one-sixtieth of the salary received at the  date  of  retirement
  for  each  completed additional year of service, during which years such
  deductions shall have been made at the rate of five per cent.