To determine how much to withhold in taxes from an employee, the employer is to use the employee's _____________.

The correct response is to utilize the employee's W-4 form to determine how much to withhold in taxes. The W-4 is specifically designed for this purpose, as it provides employers with essential information regarding the employee's filing status, number of dependents, and any additional tax withholding preferences. This form allows the employee to indicate their tax situation, which directly influences the amount that will be deducted from their paycheck to cover federal income taxes.

In contrast, the W-2 form reports the wages earned by the employee and the taxes withheld for the year, but it does not guide the withholding process itself. The W-3 form is a summary of the W-2 forms an employer submits to the Social Security Administration, and it is not used directly by employers to determine individual tax withholding. The W-5 form is for claiming exemption from withholding and is related to specific circumstances, such as certain tax credits, and is not regularly used in the withholding calculation process. Therefore, the W-4 form is the appropriate document for this task, making it the correct choice for determining tax withholding.