L’élasticité de l’impôt des personnes physiques - Approche macroéconomique prospective de l’élasticité nationale et de l’élasticité de l’impôt régionalisé
De elasticiteit van de personenbelasting - Prospectieve macro-economische benadering van de nationale elasticiteit en van de elasticiteit van een geregionaliseerde personenbelasting [ Working Paper 01-12 - 15/03/2012]

This Working Paper discusses the elasticity and the progressivity of personal income tax. Both concepts deal with the same object but from a different perspective: elasticity has a temporal angle, whereas progressivity has a cross-sectional angle. Progressivity is here estimated based on the distribution statistics of taxable income and taxes. In addition, a method is introduced to assess the negative relationship between progressivity and income growth. In retrospect, that relationship contributes to explain the evolution of progressivity during the past decades. Looking ahead, it can be used to project – under an unchanged policies assumption – an evolution of elasticity different from the constant elasticity hypothesis, typical of short- and medium-term models, and from the unitary elasticity hypothesis, typical of long-term models. In this context, the impact of the larger share of pensions in the tax base on progressivity is taken into account. This Working Paper also discusses the regionalization of personal income tax approved within the framework of the Institutional Agreement for the sixth Reform of the State of 2011. More specifically, it demonstrates how the treatment of elements from the tax system with a fixed dimension (zero tax bracket, tax relief) and elements with a progressive dimension (income scale) influences the specific elasticity of the regional and the federal tax shares in personal income tax.