Over the past few decades, there has been an amazing shift in how businesses are taxed. See the figure below, which is from CBO
. Businesses are more and more taxed as pass-through entities, where the income shows up on personal tax returns rather than on corporate returns. (Here
is an article discussing how the mutual giant Fidelity recently switched from one form to the other.)
This phenomenon complicates the interpretation of tax return data. For example, when one looks at the growth of the 1 percent, or the 0.1 percent, in the Piketty-Saez data, that growth is likely exaggerated because some income is merely being shifted from corporate returns. I don't know how much. If someone has already quantified the magnitude of this effect, please email me the answer. If not, someone should write that paper.
Click on graphic to enlarge.