Labour Supply and the Incidence of Income Tax on Wages

In the simple framework of a static model for equilibrium wages and labour supplies, we show that the incidence of income tax on equilibrium wages can be measured independently from the individual labour supply elasticity. This extends recent work by Blundell, Duncan and Meghir (1998) and Eissa and Liebman (1996), who estimate labour supply elasticities,and Gruber (1997), who estimates tax incidence on earnings. Our measurements are based on a large multi-level longitudinal data set of Danish private sector establishments. We find strong evidence for partial shifting of the burden of income tax from worker to employer. Higher marginal tax rates are associated with increases in gross wages and earnings. A traditional estimate of the elasticity of labour supply with respect to the net wage, which assumes no shifting of the burden of income tax, is found to overstate incentive effects by a factor of two.