On the optimal progressivity of the income tax code

Using a utilitarian steady state social welfare criterion we find that the optimal US income tax is well approximated by a flat tax rate of 17.2% and a fixed deduction of about $9,400. The steady state welfare gains from a fundamental tax reform towards this tax system are equivalent to 1.7% higher consumption in each state of the world. An explicit computation of the transition path induced by a reform of the current towards the optimal tax system indicates that a majority of the population currently alive (roughly 62%) would experience welfare gains, suggesting that such fundamental income tax reform is not only desirable, but may also be politically feasible.