Income Shifting in the Spanish Dual Income Tax*

Based on a model of behavioural response to taxes, and using the Taxpayers Panel from the Instituto de Estudios Fiscales for the period 1999-2009, we analyse whether the dual nature of the Spanish personal income tax (PIT), reinforced by the 2007 reform, has influenced taxpayers' behaviour, causing them to convert part of their general income' (from labour, real estate or economic activities) into savings income' (from movable capital or capital gains). We also extend the analysis of income shifting and study whether Spanish taxpayers also responded to the different tax treatments given to the two types of savings income (from movable capital and capital gains) until 2007, transforming savings income from one type to the other. The results of our study demonstrate three facts. First, Spanish taxpayers did respond to the different tax rates, shifting income from the general base to different forms of savings, especially capital gains. The highest-income individuals and the self-employed and business owners are the groups where this behaviour was most marked. Second, the self-employed and business owners also turned income from movable assets into capital gains, guided by their different tax rates. And third, we find signs of anticipation' and learning' effects caused by the 2007 tax reform. We believe that the results obtained will enrich the growing literature on income shifting.