This paper defines a set of indicators for distinguishing housing affordability problems resulting from high rents from those chiefly arising from low income. In place of the common ratio of rent to income, it uses a residual income indicator with indicators of over-consumption and over-paying for housing services. The indicators are computed for a sample of renter households in Switzerland, one of the countries with the greatest rental share. They help define more precisely who needs general income assistance and who needs specific housing aid (only one fourth of the former).