The third in series of infographics I am designing to illustrate the average federal tax rate applied to different salaries. This time I am graphing the average tax rates for married couples filing a joint tax return but with 2 incomes (same salary for each).
The difference between this graph and the couple with one income is that the the Social Security Tax cut off is now $213,600 (instead of $106,800), which increases their average SSN tax rate and their combined tax rates.
The income tax graph is created from the 2009 tax schedule for a couple filing jointly or qualifying widow(er):

which you can find from the IRS Tax Tables here while the information about the social security and medicare tax can be found here.

Visualizing Economics was started in 2006 by 
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