Click on 'File a Return" in the Withholding account box. 2. Navigate to the appropriate filing period to file a return (Forms IL-941 and IL-941-X). 3.Employers use Form 941 to: Report income taxes, Social Security tax, or Medicare tax withheld from employee's paychecks. Employer S files Form 941X on January 6, 2012 to correct the overpayment using the adjustment process. Complete the contact form page and attach a file for ONE of the following proofs of payment for each payment. This guide provides the basics of the 941 form, instructions to help you fill it out, and where you can get help meeting all your payroll tax obligations. Generally, in order to receive a refund for an overpayment of FICA tax, an employer must repay or reimburse its employee the employee's portion of FICA tax.