Self employment taxes are comprised of two parts: Social Security and Medicare. For 2009, you and your employer each pay Social Security taxes of 6.2 percent on the first $106,800 of your covered wages. You each also pay Medicare taxes of 1.45 percent on all your wages - no limit. If you are self-employed, your Social Security tax rate is 12.4 percent and your Medicare tax is 2.9 percent on those same amounts of earnings but you are able to deduct half of that as if you were your own employer. Use this calculator to estimate your self-employment taxes.