This paper measures the effect of changing the marginal tax rate on earned income on the supply of labor to the informal sector with the purpose of evading taxation. Unlike any previous study, we do this by directly measuring the effect of a Danish 2010 tax reform that changed the marginal rate of taxation of earned income from 63 percent to 56 percent. The analysis is based on longitudinal survey data collected over the period 2009-2012. In each survey round we asked people about their activity in the informal sector. The effect of the tax reform on informal sector activity is measured by comparing the evolution of informal sector activity from 2009 to 2012 for people who in 2009 paid the middle and top rate of tax with people who did not. We find that there is no connection between the marginal tax rate and the supply of labor to the informal sector. As part of the survey we asked people about their perceived marginal net-of-tax income, and we show that the survey participants did not change their perception of their marginal net-of-tax income from before to after the reform. This suggests that the respondents in our survey were not aware of the implications of the reform. We also investigate the effect of the introduction of a tax deduction for the purchase of selected services on the supply of labor to the informal sector. Here again we are unable to detect any effect. Overall, our results indicate the changing the after-tax price of services is not an effective way of reducing undeclared work.
