June 26, 2025
Federal law requires new employees to complete IRS Form W-4 so employers can withhold the correct amount of federal income tax.
Form W-4 determines how much federal income tax is withheld from an employee’s paycheck.
Each new employee must complete a Form W-4 when they begin employment. The form asks for information such as marital status, dependents, and any additional withholding amounts.
Employers use the W-4 to calculate payroll withholding using IRS tax tables.
Employees may update their Form W-4 at any time, especially if their personal or financial situation changes (e.g., marriage, new child, second job). They may also want to consider using the IRS' Tax Withholding Estimator as a tool to estimate the federal income tax you withheld from each paycheck.