Alexandria Ocasio-Cortez hit headlines last week for advocating marginal income tax rates “as high as 60% or 70%” on those earning $10 million plus per year. Under her plan, revenues from such a policy would be put towards funding a “Green New Deal.”
Matt Yglesias, Paul Krugman and Noah Smith were quick out of the blocks to defend the idea of massive marginal tax hikes on high earners as simply sensible, mainstream economics. They appealed to the work of economists Peter Diamond, Emmanuel Saez, Thomas Piketty and others, who have set out the case for very high marginal tax rates on top incomes in academic journals over the last two decades.
These economists have indeed recommended the optimal marginal tax rate for the top 1% of income earners in the U.S. should be a combined (federal, state and local taxes) rate of 73 percent or higher – designed with the aim of maximizing revenue from top taxpayers.
But their recommendation is not analogous to jacking up marginal federal income tax rates on very high earners in our current code. Furthermore, their result depends on highly contentious philosophical positions and economic assumptions.