Social rental housing ought to function as safety net for the lower income groups in the housing system. However, the Dutch housing system has a relatively large social housing stock in relation to other housing systems in Europe – larger than would be required for a safety net for lower income groups. Hence, households which are financially able to purchase market housing occupy social dwellings. The Dutch government proposed four policy changes to improve the accessibility of the social housing market for low income families. The effects of these policy changes are uncertain due to unpredictable housing move behaviour of households (which is also influenced by economic and demographic uncertainty). A system dynamics model, taking this unpredictability to some extent into account, was created to explore the effects of the policy changes until 2020. Latin Hypercube simulations suggest that these measures improve the allocation of low income households to the social housing sector, while the uncertainty ranges of the absolute number of low income households of in the social housing sector do not differ among scenarios.