From and after the date of the execution of the agreement, the officer or board paying the salary of a member of division B shall withhold the following from such salary:
(1) Four percent of such salary, which shall constitute the contribution of the member to this system with respect to retirement and other benefits payable under this system. The officer or board so withholding such percentage of salary shall without delay deposit the same in the State and County Officers and Employees’ Retirement Trust Fund.
(2) The percentage of such salary, which shall constitute the contribution of the member required for social security coverage as now or hereafter fixed by relevant federal statutes. The officer or board so withholding such percentage of salary shall submit the same without delay to the Internal Revenue Fund as directed by the Social Security Administration.
(3) Any contributions made by a member of division B during the calendar years 1956 and 1957, for state and county retirement contributions, in excess of 4 percent of the member’s total salary shall be returned to the member on the effective date of the member’s retirement or applied to any shortage which may exist in the member’s retirement account.