David and Ian Nelson from Fife have both won their legal battles challenging the bedroom tax, which would have seen them lose 14% of their housing benefits - about £500 each a year.
The two brothers from Fife have become two of the first people in the UK to successfully challenge the welfare reforms.
Deputy First Minister Nicola Sturgeon described the ruling as "hugely significant".
David, 57, from Glenrothes, said his spare room was too small to be taxed. At 50 sq ft there is just room for a single bed while still being able to open the door.
Ian, who only has one leg, successfully argued his "spare" room should be turned into a wet room as he struggles to get into a bath.
Last week, the brothers were told that they would not have their housing benefits cut as the rooms in their house were exempt.
The hearings were held at Pathhead Church in Kirkcaldy, where Simon Collins QC, an independent tribunal chairman ruled that there should be a minimum bedroom size and that rooms that have a long established use should be taken into account.
Despite the UK Government refusing to define a minimum bedroom size, Mr Collins ruled that a room under 50 square feet is not a bedroom and a room measuring between 50 and 70 square feet is only suitable for children under 10.