When an employer pays there FICA taxes do they include the previous month's amounts if the payroll period was paid the following month. Example. Payroll Period dates are 11/21 thru 12/2. FICA is due by 12/15 for the previous month. Do you include the amount set aside for the 11/21 thru 11/30 portion of the payroll that was paid to the employee's for the period ending 12/2?