How to Figure Your Own Payroll Deductions

Figure the Social Security tax that will be subtracted from your gross wages. The Social Security rate is 6.2% (.062). For example, if your gross earnings are $640 for the pay period, your calculation would be 640 x.062 = 39.68.

Calculate how much Medicare tax, which is 1.45% (.0145), to withhold from your gross earnings. For example, gross wages of $640 will be 640 x .0145 = 9.28.

Subtract any pre-tax deductions from the gross earnings. For example, if your gross earnings are $640 and you put $40 per pay period into a 401(k) or another qualifying plan, you would take 640 – 40 = 600, which will be the gross earnings that you use to calculate your federal and state tax withholding. If you have no pre-tax deductions, skip to the next step (and in this example, you would use $640 to figure your federal and state taxes rather than the $600 shown below).

Figure the federal tax using the status and allowance information you entered on the W-4 form that was filled out when you were hired by the employer. For example, if you claimed single status with one allowance and are paid bi-weekly, you would find the correct tax in a table in Publication 15-T, starting on page 11. For a single person, paid bi-weekly claiming one allowance, the federal tax on $600 is $23.

Calculate the state tax by using your state's tax tables. For example, if your gross income after pre-tax deduction is $600 and you live in Wisconsin, claim one exemption on your W-4, are paid biweekly and are single, your tax would be $22.40.