Home buyers will find it easier to qualify for an adjustable rate mortgage over a fixed rate mortgage. Adjustable rate mortgages (ARMs), also called variable rate mortgages or floating rate mortgages, are attractive to home buyers because of their low introductory interest rates. But know that interest rates are fixed to a fund index, which means your monthly installments will certainly increase. It is imperative to know which specific index a loan is tied to as you consider this option.