A number of factors help determine an individual's overall income tax burden, and the total tax liability for someone earning $100,000 can vary dramatically depending on these factors. While the same federal tax rates apply to everyone living in the United States, state tax rates -- and other rules governing state taxes -- are different in each jurisdiction. Additionally, available deductions, filing status and other issues can increase or decrease the total amount of taxes owed.
Federal Income Taxes
For a single person with a taxable income -- after deductions and exemptions -- of $100,000, 2011 federal income tax liability according to the Moneychimp tax calculator is $21,617. A $100,000 income puts such an individual in the middle of the 28 percent tax bracket, so any reduction in taxable income would result in a corresponding reduction of 28 percent of that amount in tax liability. For example, a single individual with $100,000 of gross income, who uses deductions to reduce that amount to $90,000 of taxable income, would have a 2011 tax liability of $18,817.
State Income Taxes
State personal income taxes vary widely by jurisdiction, not only in the percentage of tax due but also in which types of income are taxed, which income brackets owe taxes, and whether the tax is flat or progressive. A number of states, such as Florida and Wyoming, have no personal state income tax. An individual making $100,000 in a state without state income tax will owe no income tax to the state. In Colorado, which has a flat 4.63 percent state income tax, an individual with $100,000 in Colorado taxable income will owe $4,630 to the state. In other states with progressive tax schemes or large exemptions, the amount of tax will be based on a more complex formula.
FICA or Self-Employment Taxes
FICA taxes include Medicare taxes and Social Security taxes, and are withheld by employers with each paycheck. In 2011, the FICA tax percentage for employees is 5.65 percent, which was reduced from 7.65 percent in 2010. An individual making $100,000 in income will thus in 2011 owe $5,650 in FICA taxes. It is important to note that FICA is withheld and owed based on gross income and not net taxable income. Thus deductions, tax credits and similar adjustments can not be used to reduce FICA liability. Self-employed individuals, instead of having FICA taxes withheld by employers, must pay self-employment taxes which serve a similar purpose. Because these taxes include both an employer's an employee's share, they are higher: The 2011 self-employment tax rate is 13.3 percent.
Deductions, Filing Status and Other Factors
Once an individual making $100,000 has calculated her taxes based on the basic components above, there are still a number of other factors that can increase or reduce overall tax liability. Local taxes, such as a city tax, are applicable in some jurisdictions. An individual's filing status, single vs. married, will affect the amount of taxes owed, as will the number of dependents in a household. Various tax credits and deductions, such as those for education and medical expenses, can also significantly decrease tax liability.
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