Rent controls and rent setting regulation in different contexts incorporate and balance different aims, in particular when securing affordability and the effective distribution of scarce housing by incorporating market mechanisms. As rent policy is frequently discussed in terms of affordability or market functioning in broad terms, small-scale distributive socio-spatial effects are often not regarded. In this paper, three strategies under the new rent sum policy are compared against the former policy and practice for Amsterdam, the Netherlands, to observe the effects of distributive justice. The new rent policy partly decentralizes rent increase decisions from the national level to local authorities and housing associations. Using microdata on all social housing units and their tenants' distributive justice, outcomes under the former policy and practice are observed for a 6-year period (2008-2014) and the effects of three different rent increase strategies under the new rent sum policy are forecasted for the same period, combining an ex ante and an ex post evaluation. The possibilities for housing associations to vary rent increases for different groups of tenants in order to improve distributive justice outcomes are explored. Results show that all three possible strategies decrease the observed affordability gap between new and long-term tenants. Valuing the distributions of these strategies by applying two different standards for distributive justice shows the rent sum policy may only result in modest improvements.