(18.03.3025) This brief aims to improve our understanding of how population ageing affects the financial sustainability of health systems, focusing on its likely impact on affordable access to health care (‎financial protection)‎. It uses the Population Ageing Financial Sustainability Gap for Health Systems (‎PASH)‎ Simulator to forecast the impact of population ageing on health system revenue and spending between now and 2060 to estimate the likely size of the ageing-related health financing gap in selected countries in Europe (‎Bulgaria, Italy, Slovakia, Slovenia and Spain)‎. It then simulates the impact of filling this gap through out-of-pocket payments on the incidence of impoverishing and catastrophic health spending – two key indicators of affordable access to health care – and discusses the policy implications for countries in Europe and beyond.