Use lines 3, 4, and 5 below to have additional withholding per pay period under special agreement with your employer. You are required to file withholding certificates when you begin employment with the City of New York or transfer to another agency.Complete Form W-4 so that your employer can withhold the correct federal income tax from your pay. Every employee is required to complete a federal Withholding Allowance Certificate (W-4), which can also be utilized for state and local withholdings. Complete Form IT-2104 each year and file it with your employer if the number of allowances you may claim is different from federal Form W-4 or. Instructions. Form IT-2104, together with your employer's withholding tables, is designed to ensure that the correct amount of tax is withheld from your pay. Employee's Withholding Certificate. Step 2: Complete an Employment Verification Request Form. Keep all records of employment taxes for at least four years after filing the 4th quarter for the year. Both employers and employees should keep up to date on these changes.