La scomposizione dell'effetto redistributivo in effetto verticale, orizzontale e di riordinamento : analisi della recente letteratura e verifica empirica

The decomposition of the actual redistributive effect of a tax system has been introduced in order to analyze the potential vertical effect that a tax system would achieve if horizontal and vertical unfairness were not present. van De Van, Creedy and Lambert (2001) suggest choosing as the optimal bandwidth the one which maximizes the potential effect V (which depends on the bandwidth). We consider the three most important decompositions of the redistributive effect (Urban and Lambert 2008) and we suggest looking for the bandwidth where the ratio between the maximum distance among the three potential vertical effect definitions and the minimum among them is minimum; our criterion seems to be more stable in identifying bandwidths, when comparing different tax systems. Making use of a microsimulation model based on microdata provided by the Bank of Italy in its Survey on Households Income and Wealth in the year 2006, in this paper we compare the 2006 and 2007 Italian personal income tax systems. The two tax systems are considered both under the point of view of individual tax payers and that of families, by applying an equivalence scale. The 2007 tax system is characterized by a greater redistributive effect (both actual and potential): however it presents also stronger horizontal inequity and reranking