Which form is primarily used for tax withholding information?

The W-4 form is essential for employees as it provides their employers with the necessary information to determine the amount of federal income tax to withhold from their paychecks. This form allows individuals to indicate their filing status, the number of dependents they are claiming, and any additional amount they wish to withhold. By accurately completing the W-4, employees can help ensure that their tax withholdings align with their financial situation, which can either prevent under-withholding or over-withholding of taxes.

In contrast, the W-2 form reports an employee's annual wages and the taxes withheld by the employer. It is used by employees to file their annual tax return but does not provide information for withholding. The 1040 form is the individual income tax return form that taxpayers use to report their annual income, while the 1099 form is typically used to report income earned by independent contractors or other forms of non-employment income. These forms do not serve the primary purpose of setting up tax withholding, making the W-4 the correct and most relevant choice for that function.