We explain the positive correlation between union power and tax progressivity from a normative point of view by integrating labour market frictions and union power in an optimal taxation framework. We find that unions and redistributive taxation are complementary in the sense that they both...

This paper characterizes optimal non-linear income taxation in an economy with a continuum of unobservable productivity levels and endogenous involuntary unemployment due to frictions in the labor markets. Redistributive taxation distorts labor demand and wages. Compared to the laissez-faire,...