The biggest bi-annual demographic event in Europe – European Population Conference 2016 was hosted this time in Mainz. Pawel presented there the concept and the draft results of the joint project with Krzysztof, Magda and Oliwia: “Economic consequences of changing fertility. Insights from an OLG model”. Demographers usually try to explain reasons for fertility changes ex post. The aim of the presentation was to show how to assess ex ante gains from higher fertility for public budget assuming that we know how to persuade people to have more children. Such model seems to be relevant in the times of increasing expenditures on family policies not only in Poland but also in other EU countries.