Which document is critical for employers regarding employee wages and tax withholding?

The W-4 form is critical for employers as it is the document that employees fill out to indicate their tax withholding preferences. This form provides employers with the necessary information about the employee's filing status and the number of allowances or exemptions they are claiming. Based on this information, employers can calculate the correct amount of federal income tax to withhold from an employee's paycheck.

The significance of the W-4 cannot be overstated, as accurate withholding is essential for compliance with federal tax regulations, and it helps prevent employees from facing underwithholding penalties at tax time. This form must be kept current; employees can update their W-4 whenever their personal financial situation changes, such as a marriage or the birth of a child.

In contrast, while the W-2 provides a summary of wage and tax information that employers report annually for each employee, it is not used for determining how much should be withheld during the year. The 1099 form reports income earned outside of traditional employment, so it's not applicable for regular employee wage tracking. A payroll ledger is an internal document that tracks payments made to employees, but it doesn't directly influence tax withholding decisions.