Although the Dutch housing associations are financially independent since the mid nineties, the conduct of these organisations is still regulated by the government. As a consequence, they have several social tasks which imply uneconomic investments in dwellings as well their environment, without hazarding the financial continuity of their organisation. Selling parts of their rented dwellings is a way to finance these uneconomic investments and to guarantee their financial continuity. However, housing associations cannot unrestrictedly sell dwellings out of their housing stock. One of their tasks is to provide accommodation for households who are not able to provide in their own housing, like households with a low income. So a minimum number of dwellings are required in order to guarantee housing for those households. This paper presents a model to calculate the minimum required number of dwellings, by combining household incomes, housing prices and the changing distribution of dwellings. The model can be applied at multiple geographical based levels, for instance at municipality level. The paper will go into the model and its outcomes. After some background information, it starts with two different theoretical calculations of the match of housing prices and household incomes. The housing prices are calculated by using values determined under the Dutch Real Estate Appraisal Act. Next it calculates three scenarios based on the theoretical combinations and the current distribution of housing among renters and owners as well as taking into account the way users move house. These scenarios generate different outcomes in regard to the number of social rented dwellings that could be sold. Which scenario is best used differs per region. After presenting the outcome of the model the paper ends with a discussion on limitations of the model and its implication for the key question: to sell or not to sell social rented housing.