This article offers a new approach of the microsimulation analysis of fiscal systems. Using a model which enables us to include four major French taxes (the VAT, payroll taxes, income tax and the CSG, a tax on all types of income) and the bootstrap technique, we compare the redistributive impact of an increase in fiscal revenue for different fiscal instruments. The well known results of the microsimulation literature on French fiscal reforms are confirmed: most notably the strongly redistributive impact of the income tax and the regressive one of the VAT. Our methodological contribution consists in the construction of confidence intervals for the semi-elasticities of Gini coefficients to the use of each tax.Cet article propose une extension...