What is the W-4 form used for?

The Employee Withholding Allowance Certificate, or form W-4, tells the employer the marital status, number of withholding allowances and any additional amount to use when calculating the amount of federal income tax to deduct from an employee's paycheck. Missing or incomplete W-4s require employers to withhold at the highest rate.

Employees can revise a W-4 when changes in status dictate, such as marriage, a change in the number of dependents, or a change in the itemized deductions or anticipated tax credits of the employee. For Spanish-speaking employees with proper documentation to work in the United States, W-4 forms can be supplied in Spanish.