Federal income tax is withheld from the pay of almost all employees. Employee pay is inclusive of salaries and wages, bonuses, commissions, and vacation allowances. It is the responsibility of the employer to provide the employee with a W-4 at the onset of their employment. The determination of tax withheld is computed from the information provided on the W-4. The employee must inform the employer of their withholding status (married or single), and the number of exemptions they will be claiming.

Employees also have the option to have an additional amount withheld from their pay. If, over the course of an employee's employment, they wish to change or adjust their withholding rates, they may simply request to complete a new W-4. Publication 919