Municipalities, especially those with a large share of low-income households and a high share of unemployment, may not have the financial and organisational capacity to supply and maintain social housing. In Poland, for example, municipalities are responsible for the supply and maintenance of social housing, but due to their scarce financial resources, the supply of affordable housing has remained a major challenge, especially in mid-sized cities (OECD, 2011b). This takes the form of demand-side subsidies (e.g. tax relief on paid rent for tenants) or supply-side subsidies (e.g. favourable treatment of rental income for landlords).