Four or more mortgaged buy to let properties would make you hey portfolio landlord. in order to get a buy to let mortgage most high street lenders will also require you to be classed as an “experienced landlord” meaning you would need to have owned a buy to let property or have received rental income for six months. Also, a lot of lenders require you to be an “owner occupier” of your own residential property first before they would allow you to qualify for a buy to let mortgage.