This paper provides estimates of the implicit fiscal assets as well as of the evolution over time of fiscal costs and revenues related to tax-favoured retirement saving regimes in 17 OECD countries, taking into account current and future contributions, asset accumulation and withdrawals, all of which will be strongly influenced by future demographic developments. The main results show that in the case where tax incentives are assumed to lead essentially to saving diversion rather than creation, the net budgetary cost of tax-favoured schemes would remain large, despite the sharp rise in revenues collected from withdrawals as population ages. The paper shows that this cost would significantly be reduced if tax-favoured schemes succeed in promoting additional private savings. It then explores a number of policy options to maximize the amount of additional saving ...