Adjustable Rate Mortgage An adjustable rate mortgage or variable rate mortgage is a loan secured on a property (house) whose interest rate and so monthly repayment vary over time. Other forms of mortgage loan include interest only mortgage, fixed rate mortgage, discounted rate mortgage and balloon payment mortgage. Adjustable rates transfer part of the interest rate risk from the lender to the borrower. They can be used where unpredictable interest rates make fixed rate loans difficult to obtain. The borrower benefits if the interest rate falls and loses out if interest rates rise