Tax fraud is intentionally underreporting or failing to report income. This is called nonresident withholding.Information on the Foreign Investment in Real Property Tax Act of 1980 (FIRPTA) and how it affects a foreign person with real property interest. If you notice an issue with your tax forms, please complete the Request to Correct or Dispute Tax Forms. We will research your case within 60 days. This publication is designed to provide employers with general guidance regarding Colorado wage withholding requirements. The IRS Tax Withholding Estimator is available to help employees determine the proper amount of federal income tax withholding. Find answers to frequently asked questions, submit a question to customer service, find our mailing address and customer service hours. It's also illegal to purposely misrepresent or supply fraudulent information on corporate tax returns. How the income calculator works.