Earlier studies of labour supply in a life cycle context have typically either neglected taxes completely, or represented the income tax by a linear function. The present paper studies how the qualitative conclusions of a “traditional” life cycle model of labour supply are changed when a nonlinear tax is introduced into the model. It is shown that the comparative statics results, and the characterization of the consumption and labour supply paths, depend critically on whether capital and labour income are taxed jointly or separately, and on the progressivity (nonlinearity) of the income tax. Few of the results valid for a linear income tax carry over to the nonlinear case.

Choice models with nonlinear budget sets are important in econometrics.In this paper we propose a nonparametric approach to estimation of choice models with nonlinear budget sets.The basic idea is to think of the choice, in our case hours of labor supply, as being a function of the entire budget set.Then we can ac- count nonparametrically for a nonlinear budget set by estimating a nonparametric regression where the variable in the regression is the budget set.We reduce the dimensionality of this problem by exploiting additive structure implied by utility maximization with convex budget sets.This structure leads to a polynomial con- vergence rate for the estimator.We give asymptotic normality results also.The usefulness of the estimator is demonstrated in Monte Carlo and empirical work, where we find it can have a large impact on estimated effects of tax changes.

Choice models with nonlinear budget sets provide a precise way of accounting for the nonlinear tax structures present in many applications. In this paper we propose a nonparametric approach to estimation of these models. The basic idea is to think of the choice, in our case hours of labor supply, as being a function of the entire budget set. Then we can do nonparametric regression where the variable in the regression is the budget set. We reduce the dimensionality of this problem by exploiting structure implied by utility maximization with piecewise linear convex budget sets. This structure leads to estimators where the number of segments can differ across observations and does not affect accuracy. We give consistency and asymptotic normality results for these estimators. The usefulness of the estimator is demonstrated in an empirical example, where we find it has a large impact on estimated effects of the Swedish tax reform.

The elasticity of taxable income is vital when predicting the effect of taxes. Bunching at kinks/notches has been used to estimate this elasticity. We show that when the preference distribution is unrestricted, bunching at a kink or a notch is not informative about the size of the elasticity, and neither is the entire distribution of taxable income. Bunching identifies the taxable income elasticity when the preference distribution is correctly specified across the kink and provides bounds under restrictions on the preference distribution. We find wide bounds in an empirical example based on upper and lower bounds for the preference density.