Form W-4

Form W-4 is a federal tax form employees fill out to tell their employer how much federal income tax to withhold from their paycheck. The IRS form collects personal details like filing status, number of dependents, and any additional income sources that affect tax liability.

HR departments use that information to calculate the right withholding amount throughout the year. Employees submit a new W-4 when they start a job or go through a life change that affects their tax situation.