11—46.5 (70A) Deduction limits and frequency. Authorized deductions must be a minimum of $1. The frequency of the deductions must be compatible with the affected payroll system. All payroll deductions must be made in equal amounts on a monthly basis or be made on a basis compatible with the payroll system. The deduction will be made only for the amount of insurance premiums and shall not include amounts for any other purpose, such as organizational dues or membership fees.