Resumen: Based on a model of behavioural response to taxes, and using the Taxpayers Panel of the Institute of Fiscal Studies for the period 1999–2009, we analyse whether the dual nature of the Spanish Personal Income Tax (PIT), reinforced by the reform of the year 2007, has influenced taxpayers’ behaviour, causing them to convert part of their “general income” (from labor, 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 treatment given to the two types of savings income (movable capital and capital gains) until 2007, transforming savings income from one type to another. 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, self-employed and business owners also turned income from movable assets into capital gains, guided by their different tax rates. And third, we have found 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. Idioma: Inglés DOI: 10.1111/j.1475-5890.2017.12147 Año: 2018 Publicado en: FISCAL STUDIES 39, 1 (2018), 95-120 ISSN: 0143-5671 Factor impacto JCR: 1.164 (2018) Categ. JCR: ECONOMICS rank: 192 / 363 = 0.529 (2018) - Q3 - T2 Categ. JCR: BUSINESS, FINANCE rank: 69 / 103 = 0.67 (2018) - Q3 - T3 Factor impacto SCIMAGO: 0.625 - Accounting (Q2) - Finance (Q2) - Economics and Econometrics (Q2)