In this chapter, we will explore whether it is possible to account for the intuition that a contribution rate of the “active” population to the benefit of the elderly can be said to be unjustly high. This is one possible lens through which to look at issues of justice related to population ageing. The chapter follows three steps. First, it looks at issues of justice in case of a population with high longevity devoid of any heterogeneity in longevity. Second, it introduces unequal longevities within each birth cohort, without any increase in average longevity between birth cohorts. Third, it adds the fact of increasing average longevity over time. The chapter shows that the core problem faced by a high contribution rate – e.g. to fund pension schemes – is associated with heterogeneity in longevity, which can obtain even in the absence of population ageing. We even show that the latter surprisingly softens the dilemma faced by a theory of justice concerned with inequalities over complete lives between short-lived and long-lived individuals.