A staff provident fund was established at the Jordan Cement Factories Co. Ltd. This Fund`s system is based on the following:
First: (10%) is deducted from basic salary and (15%) is paid by the company.
Second: An employee may borrow (50%) of his financial rights in the provident fund after ten years of service (Outstanding advance).
Third: An employee has the right to withdraw his entire balance (Deductions from salary and company payments) after fifteen years of service.
Fourth: An employee`s entire balance (Deductions from salary and company payments) is returned to him upon separation from service.
Fifth: Annual profits shall be divided among staff members at the end of every fiscal year.
Based on the above information, how should staff members who are participants in this fund calculate Zakah due on their money?