Editor's note: Edward J. McCaffery is Robert C. Packard Trustee
Chair in law and a professor of law, economics and political
science at the University of Southern California. He is the
author of "Fair Not Flat: How to Make the Tax System Better and
Simpler." (CNN) -- In a recent opinion column on Phil
Mickelson's tax comments, I pointed out that some of the working
poor face marginal tax rates "approaching 90% as they lose
benefits attempting to better themselves." Readers were
incredulous, asking how it could be that in a nation with a top
federal income tax rate of 39.6% on individuals making more than
$400,000 a year, anyone could face a 90% rate. It is true.
Marginal tax rates, especially for those below the top rate
brackets, are chaotic, confusing, and all over the map. As a
result, some of the working poor face extremely high rates on
their next dollar earned. Tax scholars and economists have long
known this. Dan Shaviro of NYU published a study in 1999 showing
marginal tax rates above 100% on the work