To elect an Arizona withholding percentage, an employee must complete Arizona Form A-4, and submit it to their employer. Withholding returns must be filed electronically for taxable years beginning from and after December 31, 2019.The Tax Department is streamlining withholding tax and wage reporting forms and Web File applications. Withholding Tax Forms for 2017 Filing Season (Tax Year 2016). (Please note the Office of Tax and Revenue is no longer producing and mailing booklets.