- 1). Obtain a copy of the IRS Form W-4 Personal Allowances Worksheet. Complete lines A through G, add up the numbers on lines A through G and enter onto line H.
- 2). Use the Deductions and Adjustments Worksheet on page 2 if you are planning to itemize your deductions. Complete the Two-Earners/Multiple Jobs Worksheet on page two if you work two jobs or your spouse is employed.
- 3). Use the IRS Withholding Calculator as an alternative to doing the calculations yourself, especially if you have the type of circumstances that would require you to use the worksheets on page two of the W-4.
Source...