23rd
In the first part of the paper, D&S analyze the optimal tax rate on top earners. And they argue that this should be the rate that maximizes the revenue collected from these top earners — full stop. Why? Because if you’re trying to maximize any sort of aggregate welfare measure, it’s clear that a marginal dollar of income makes very little difference to the welfare of the wealthy, as compared with the difference it makes to the welfare of the poor and middle class. So to a first approximation policy should soak the rich for the maximum amount — not out of envy or a desire to punish, but simply to raise as much money as possible for other purposes.
Now, this doesn’t imply a 100% tax rate, because there are going to be behavioral responses – high earners will generate at least somewhat less taxable income in the face of a high tax rate, either by actually working less or by pushing their earnings underground. Using parameters based on the literature, D&S suggest that the optimal tax rate on the highest earners is in the vicinity of 70%.
