Économie et Statistique n° 481-482 - 2015Microsimulation applied to fiscal and social policies
The scope and limitations of the Taxipp model for the analysis of tax redistribution
This article presents the Taxipp model, a microsimulation model of French taxes and social contributions which enables the classical simulation of past or present counterfactual legislations on a representative sample of the French population. The model differs from standard static microsimulation approaches in that it pays special attention to the imputation of the distribution of high incomes and calibrates the data to the aggregate information from the national accounts. The model therefore makes it possible to provide micro-level breakdowns of measures of all taxes and social contributions, in a manner consistent with the macroeconomic approach to taxation presented by the national accounts. Furthermore, it makes it possible to present detailed analyses of tax reforms targeting the top of income distribution, on which public debate often focuses. Yet this type of exercise has its limits. The first is the unavoidable nature of incidence hypotheses, in particular for taxes collected nominally from companies; the lack of consensus on the fiscal incidence of corporation tax leads to significantly different variants. The second limit arises from contradictions in the different aggregate sources (national accounts, tax sources), which are difficult to reconcile. These limits do not have a nullifying effect; on the contrary, they open many avenues for future research aimed at improving the relevance of micro and macro approaches in the analysis of social and fiscal systems.