I know quite a few couples who have bought a new property but are keeping their old one/s to rent out. When I looked into it, as had considered doing similar, the numbers did not stack up at all. The the profit would have been so minimal that it was not worth the risk. A big part of this was the conditions that came with a buy-to-let mortgage and bigger deposit required. Does anyone know if a lot of people are actually renting out while on their residential mortgages rather than switching to buy to let? Online it says this is very risky, but I wonder if a lot of people are doing it anyway...