The Beldebt project aims at addressing again the old issue of the sustainability of public finances of Belgium in order to take into consideration changes, both institutional level and in the economic context, which intervened after 2010. The institutional changes, both at European (new Stability and Growth Pact, European Semester, the Fiscal Compact) and national level (Sixth Reform of the State) added new dimensions to the issue of the sustainability of public finances. Changes in the EU governance, towards a tougher system of rules and in principle stronger enforcement mechanisms, aim at a framework where sustainability of public finances is monitored systematically, risks are controlled and debt reduction is (re-)stated as an obligation. The prolonged crisis and the following recession make it difficult to assess whether the system is being really effective but the degree of discretion at national (which is not only federal) level in defining domestic economic policies has certainly diminished.