to the employee at the end of the year, and if they are overwitheld, the employee gets a refund for the overpayment of taxes. There is a basic formula for estimating the taxes that need to be paid, but various tax factors may cause it to be wrong, such as dependents, tax deductions, or income from other sources. The W-4 form allows the employee to pick an exemption level to reduce the tax factoring (to avoid overpayment), or specify an extra amount above the standard number (to avoid underpayment). The form comes with two worksheets, one to calculate exemptions, and another to calculate the effects of other income (second job, spouse's job). The bottom number in each worksheet is used to fill out two if the lines in the main W4 form. The main form is filed with the employer, and the worksheets are discarded or held by the employee. References Stationery Mathematics education Accounting systems