Three important income reforms have been carried out in Poland since 2007, involving a reduction in social insurance premiums, the introduction of a tax break for families with children, and the replacement of three personal income rates (19%, 30% and 40%) with two rates (18% and 32%). Morawski uses a tax-benefit microsimulation model (SIMPL) and household budget data from 2006 to examine the results of the 2009 income reform. By comparing two hypothetical breakdowns of disposable household incomes, the author shows that the reform has primarily benefited the wealthiest households, while the incomes of many poor households have not changed. In all, the incomes of more than 15 percent of the households have not changed after the reform, Morawski says. At the same time, analyses show that the reform has benefited many single-member and pensioner households which did not benefit from previous reforms. The results described in the paper were obtained with the assumption that the supply of labor would not change. Labor market analyses show that such an assumption is justified in the case of the 2009 tax reform, the author says.