Information about Form W4, Employee's Withholding Certificate, including recent updates, related forms and instructions on how to file. Form W4 tells your employer how much tax to withhold from each paycheck.Learn more about how and when to adjust your W-4. Allowances are no longer used for the redesigned Form W4. This change is meant to increase transparency, simplicity, and accuracy of the form. The new form has five steps. Employees must fill out step 1 and step 5. To apply for an exemption, call the Bexar Appraisal District at 210-224-2432. Complete a new Form W-4, Employee's Withholding Allowance Certificate, and submit it to your employer. You may need to fill out a W-4 state form on top of a W-4 federal form.