The credibility of commitment and optimal nonlinear savings taxation

Previous studies that examine optimal nonlinear taxation of savings/capital have assumed either full-commitment or no-commitment by the government. This raises the question as to whether the results under full-commitment and no-commitment provide upper and lower bounds on the optimal marginal savings tax rates. This paper shows that they do not. Specifically, we consider an infinite-horizon overlapping generations model in which agents attach some probability to whether or not the government can commit. When these probabilistic beliefs differ among high-skill individuals, the optimal steady-state marginal savings tax rates may fall outside those under the polar cases of full-commitment and no-commitment. Our numerical analysis finds that this theoretical possibility can occur under a baseline calibration with empirically plausible values of model parameters, and that it remains qualitatively robust with respect to various parametric changes.