From a policy perspective, a thorough discussion and assessment of the sustainability of public finances in the EU seems the more relevant today. The European Commission's Fiscal Sustainability Report contributes to this discussion by examining fiscal sustainability challenges faced by Member States over the short, medium and long run. The underlying drivers of the challenges are thoroughly analysed in the report. Even when the fiscal position of a country appears to be sound, sudden episodes of fiscal stress may occur following the materialisation of fiscal or macro-financial risks.... Medium-term sustainability challenges are assessed by having regard to the underlying country's initial budgetary position, the level and projected evolution of the country's public debt and projected implicit liabilities related to an ageing population. In the long run, on the other hand, it is not the level of debt that matters most, but its projected evolution, taking also into account the projected cost of an ageing population. The identification of the nature, the scale and the urgency of the challenges faced by individual Member States is provided in the report as a key ingredient to support the formulation of appropriate policy responses. In this respect, the report also provides input to the EU's process of multilateral economic surveillance in the context of the European Semester.