Because amortizing mortgages begin with minimal principal pay downs and increase over the term of the mortgage, there is little advantage to the mortgagor in the early years of an amortizing mortgage. Given a 6% interest rate and 30-year amortization, the principal pay down for a three-to-five year would be in the 4% to 7% range. As a result, interest-only mortgages are a useful tool if the expected holding period for the property is within that range.