What form is used to determine the amount of income tax withheld from a person's payroll check?

The W-4 form is used to determine the amount of income tax that should be withheld from an employee's paycheck. When an employee starts a new job or experiences a change in their financial situation, they fill out a W-4 to provide their employer with the necessary information, such as marital status, number of dependents, and any additional amount they wish to withhold. This helps the employer calculate the correct amount of income tax to deduct from each paycheck, ensuring that employees meet their tax obligations throughout the year.

In contrast, the W-2 form serves as a summary of an employee's earnings and the taxes withheld for the entire year, which is provided to employees at the end of the tax year for filing their tax returns. The 401K form relates to retirement savings plans and does not determine income tax withholding. The W-9 form is used primarily for providing taxpayer identification information for independent contractors or businesses rather than for payroll tax withholding.