What Is Form W-4?

Form W-4 tells your employer how much federal income tax to withhold from your paycheck. You fill it out when you start a new job and should update it whenever your situation changes — marriage, divorce, a new child, or a significant income change. The form asks about dependents, other income, and deductions so your employer can withhold the right amount. Getting withholding right helps you avoid a big tax bill or a large refund at filing time. Use the IRS Tax Withholding Estimator at IRS.gov to check your withholding.