In the years to come, the ageing of the French population will lead to an increase in the number of dependent elderly people. Assuming that the average dependent life span remains stable, 1,200,000 people will be dependent in 2040, compared with the current figure of 800,000. Today, the care of these people combines both family solidarity, via care from family members, and collective solidarity, via services such as personal autonomy benefit. These two forms of solidarity will evolve in the future. On the one hand, family solidarity could wane, since the number of potential carers per dependent elderly person will tend to decrease. On the other hand, the future of spending on personal autonomy benefit will largely depend on the way in which it is indexed.