The growing number of immigrants in the Madrid region raises several questions concerning the welfare of future native generations. The debates shift from increasing concern about the congestion of public services like education or healthcare, to how immigration helps to ease tension in relation to financing those services and other benefits to the region's general welfare. In order to evaluate the global effect, our analysis uses a generational accounting method which is applied to different productivity, interest rate and growth scenarios. The results show that the impact of immigrants is positive, with intergenerational distribution towards the currently most active taxpayers.