Social Security Tax

• Social Security tax is deducted from your paycheck under the Federal Insurance Contributions Act of 1939 or FICA. This tax is used to fund Social Security retirement benefits for retirees currently receiving payments. According to Money Zine's website, as of January 2011, the Social Security tax rate deducted from your paycheck is 4.2 percent up to the first $106,800 earned in the year. You are not required to pay this tax on any amount earned over this dollar cap.
  
  

Medicare Tax

• You are also required to pay a Medicare tax on your earned income. This tax is used to fund government-run health insurance programs for senior citizens. Medicare tax is included in the FICA tax that also houses the tax you pay for Social Security. As of January 2011, the tax rate for Medicare on earned income is 1.45 percent. Unlike the tax on Social Security, you are required to pay a Medicare tax on all of your earned income for the year regardless of how much you made.
  
  

Federal Income Tax

• The largest federal deduction on your paycheck is the federal tax you pay on your income. This figure is a sliding scale percentage based on how many dependents you claim on your IRS Form W-4 and how much money you earn. According to Money Zine, as of January 2011, the federal income tax rate on earnings up to $8,500 is 10 percent if you're single with no dependents. The tax rate increases to 15 percent for income over $8,500 and under $34,500.
  
  

Self-Employed Taxes

• If you earn income from self-employment, the federal income tax rate still applies to you as normal. You may be required to pay a higher Social Security and Medicare tax on your income than those who receive paychecks directly from an employer. According to the Social Security Administration's website, as of January 2011, the Social Security tax rate is 10.4 percent for the first $106,800 earned if you are self-employed. The Medicare tax rate if you are self-employed is 2.9 percent.