The dynamic micro simulation model SADNAP (Social Affairs Department of the Netherlands Ageing and Pensions model) is being developed for calculating the financial and economic implications of the ageing problem and of the policy measures considered. A micro simulation model, as compared to macro-oriented models, can give more detailed information on the ageing problem and on the redistributive effects of policy options, which can be used in the evaluation of those options. The model uses administrative datasets of all Dutch public pensions and entitlements for all public pensions and a large share of private pensions.