If you want to include Social Security tax in the calculation, which is a good idea, the calculation is a little more complicated. To include the Social Security tax you would have to add the Social Security withheld from your wages, found in boxes 4 and 6 of your W-2 forms, to line 61 of your Form 1040, and then divide that sum by line 22.
Most people discover that they are paying a smaller percentage than they have been lead to believe. Regardless of what you find as your answer, at least you will be dealing with facts instead of impressions or media hype.
Loren L McCann, CPA, MS (Tax)