Form W-4

Form W-4 is a U.S. tax document that employees complete when they start a new job, and can update at any time afterward, to inform their employer how much federal income tax should be withheld from each paycheck. The information provided on Form W-4, including filing status and any additional adjustments for dependents, other income, or deductions, directly determines the amount of tax the employer withholds throughout the year. The goal of accurately completing a W-4 is to have the correct amount of tax withheld throughout the year, avoiding a large balance due or an unnecessarily large refund when the employee files their annual tax return. The IRS periodically updates the Form W-4 design and underlying calculation methodology to make it easier for employees to achieve accurate withholding without needing to make complex manual calculations themselves. Employers are responsible for using the information provided on an employee's Form W-4 to calculate the correct federal withholding amount for each pay period, using IRS-published withholding tables or formulas. Employees can submit an updated W-4 at any point if their personal or financial circumstances change, such as a marriage, the birth of a child, or a significant change in income, and employers must apply any updated form going forward.