Here is the poop from Joel B. Slemrod. "Slemond is the Paul W. McCracken Collegiate Professor of Business Economics and Public Policy at the University of Michigan, and director of the Office of Tax Policy Research at the Michigan Business School. He was senior economist for tax policy in President Reagan's Council of Economic Advisers.
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"Chart 1 illustrates the progressivity of the overall U.S. tax system in 1985 (the latest year for which this information is available), according to two different assumptions about the shifting of taxes. Under assumption A the average tax rate generally increased with income, suggesting a generally progressive tax. Under assumption B the average tax rate actually is lowest for families in the highest income decile. The key difference between the two results is that B assumes that half of the corporation income tax is shifted to consumers, in the form of higher prices, while A assumes that all of it is borne by shareholders, who are generally high-income taxpayers. Chart 1 illustrates both the importance of the shifting assumptions and the fact that, even though the federal income tax by itself is progressive, its progressivity is overwhelmed by less progressive levies such as sales taxes and, to a lesser extent, the payroll tax."
Bogus assumption. Corporations (which don't pay taxes anyway) cannot control how much of the tax they pass on to consumers in the long run or even year over year. Market forces do that.
To properly understand your chart, I need to know how the 50% of corporate tax is apportioned to the income percentiles. Is it by income totals? per capita?
To be an honest depiction of the sharing of government, as opposed to the dishonest one it currently is, the chart should include, for each income decile, the benefits that that decile receives resulting in a "net" contribution of each group. But perhaps, like the author of the posted article, honesty isn't your goal.