§ 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 Any such written authorization may be withdrawn by such employee at any time by filing written notice of such withdrawal with such appropriate disbursing or fiscal officer.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.