We provide a microsimulation modelling tool to estimate   household responses to changes in the tax and transfer system. While our  study focuses on the effects on the supply side, we also provide an  extension  to our labor supply framework to encompass the  whole labor market by including the reaction of labor demand. We adopt a micro-based approach that allows us to study revenue and redistributive effects of tax reforms before and after taking into account labor supply reactions, both within countries and across the EU.