The purpose of Federal Withholding Form W-4 is to determine the amount of federal income tax that needs to be withheld from an employee's paycheck. By accurately completing the W-4 form, individuals can ensure that the right amount of taxes is being withheld throughout the year, thus avoiding any surprises or penalties when it comes time to file their annual tax return. This form helps employees properly adjust and control the amount withheld, considering factors such as marital status, number of dependents, and additional income sources. The W-4 form also allows individuals to claim various deductions and credits that may reduce their overall tax liability. It is essential for both employers and employees to understand how to fill out and regularly update the W-4 to ensure compliance with federal tax laws and for proper tax planning purposes.