Pensions are one of the most significant achievements of the welfare state that must be preserved. The reduction in birth rates and the aging of the population with the increase in life expectancy – that is, the time during which one is entitled to a benefit – have increased the number of beneficiaries in recent years at a faster rate than contributors. The essential principle of the pay-as-you-go system is intergenerational solidarity: that is, working individuals finance the pensions of those who have retired.