tax form prepared by an employee for an employer indicating the employee's exemptions and Social Security number, and enabling the employer to determine the amount of taxes to be withheld for the employee.
A tax form that you get from your employer and fill out to help your employer determine the amount of taxes to withhold from your paycheck (see withholding ).
A form completed by an employee to indicate his or her tax situation (exemptions, status, etc.) to the employer. The W-4 form tells the employer the correct amount of tax to withhold from an employee's paycheck.