Complete el Formulario W-4 para que su empleador pueda retener la cantidad correcta del impuesto federal sobre los ingresos de su paga. A W4 form, or "Employee's Withholding Certificate," is an IRS tax document that employees fill out and submit to their employers.Form W4 tells you, as the employer, the employee's filing status, multiple jobs adjustments, amount of credits, amount of other income, amount of deductions, Use Form I9 to verify the identity and employment authorization of individuals hired for employment in the United States. Instructions: Employees who are subject to state withholding should complete the personal allowances worksheet indicating the number of withholding. Demographic and Administrative Forms for New Employees. Form Number (if applicable), Form Description. The new form has five steps. Employees must fill out step 1 and step 5. Members may be individuals, partnerships, corporations, and any other type of legal entity.