The Tax Department is streamlining withholding tax and wage reporting forms and Web File applications. On this page, find information and forms related to withholding taxes for employers.Withholding Tax Forms and Instructions To ensure you are able to view and fill out forms, please save forms to your computer and use the latest. In order to apply the withholding to the gain, the seller must complete Form NR-AF2 (Affidavit of Seller's Gain) attesting to the amount of the taxable gain. Employee Withholding Allowance Certificate. This publication is designed to provide employers with general guidance regarding Colorado wage withholding requirements. Complete the Nebraska Form W-4N so your employer can withhold the correct Nebraska income tax from your wage payment.