Optimal size of the government: the role of the elasticity of substitution

This paper analyzes the optimal fiscal policy in an endogenous growth model with productive public services. Government expenditure, which may be subject to different degrees of congestion, is financed by distortionary income taxation. The standard result on the equality between the growth-maximizing, welfare-maximizing and first-best income tax rates holds if and only if production is Cobb–Douglas or there is proportional congestion. With non-proportional (or in the absence of) congestion, the first-best income tax is lower than the (second-best) welfare-maximizing income tax which, in turn, is lower than the growth-maximizing income tax if the elasticity of substitution is below unity. Under mild conditions these relations are reversed if the elasticity of substitution is above unity. Intuition on these results is also provided.