Section 93-C. The appropriate disbursing or fiscal officer of any municipality or other political subdivision of the state is hereby authorized to deduct from the salary of any employee of such municipality or political subdivision such amount as such employee may specify in writing filed with such appropriate disbursing or fiscal officer for payment to any credit union doing business in the state of New York, and to transmit the sums so deducted to the said credit union

The  disbursing  or  fiscal  officer  hereinbefore referred to is hereby
  authorized to make such rules and regulations governing the payments  to
  credit  unions  as  he deems necessary, such rules and regulations to be
  incorporated  in  the  employee's  written  authorization   of   payroll
  deduction,  filed  with  the  fiscal  or  disbursing  officer  of  every
  municipal corporation or other civil division or  political  subdivision
  of  the  state.  Any such written authorization may be withdrawn by such
  employee at any time by filing written notice of  such  withdrawal  with
  such  appropriate  disbursing or fiscal officer. As used in this section
  "credit union" means a non-profit organization  which  serves  only  its
  members and is chartered pursuant to the banking law of the state of New
  York,  or by the United States government pursuant to the federal credit
  union act.