When you work as an employee, the Internal Revenue Service (IRS) requires that your employer deduct money from your paycheck to cover taxes including income taxes and payroll taxes. Your state, county or city may also require tax withholding if the state has a personal income tax. Once you have determined how much the government will withhold for each tax, you can calculate how much of your paycheck you get to take home.
Complete a W-4 form to document how many personal allowances you will claim, along with your filing status. Each personal allowance decreases your income subject to income tax withholding but does not affect your FICA tax responsibilities. As of 2010, each personal allowance decreases your annual income by $3,650.
Calculate the amount of FICA taxes you owe by multiplying your paycheck amount by 0.153. For example, if you made $2,000 per paycheck and were paid biweekly, you would pay $306 in FICA taxes.
Calculate how much your personal allowances decrease your income subject to withholding by per pay period: Divide the value of the exemption by the number of pay periods per year. For example, as of 2010 if you were paid biweekly and claimed one personal allowance, you would divide $3,650 by 26 to find your weekly income subject to withholding had decreased by $140.38.
Calculate the amount of income subject to income tax withholding by subtracting the amount in Step 3 from your paycheck. For example, if you earned $2,000 biweekly and claimed one personal allowance, $1,859.62 would be subject to income tax withholding.
Compute your federal tax withholding by using the federal tax withholding tables based on your pay period and filing status. For example, if you are single and your income subject to tax withholding equals $1,859.62, you will have $282.86 withheld for federal taxes.
Contact your state, county and city departments of revenue to find out whether you will have money withheld from your paycheck for income taxes.
Total the taxes you will have withheld from your paycheck, and subtract this total to determine how much of your earnings you will receive when you get your paycheck.