An Adjustable Rate Mortgage (ARM) is a mortgage loan that is most widely known
for its low starting interest rate (when compared to the 30 & 15 year mortgage
loans). This 'low' introductory rate is used to calculate the mortgage payment
for a specified period of time. Once this introductory period is over, the
interest rate is adjusted periodically based on a preselected index. The most
commonly used index is the yield on the one-year Treasury Bill. The new interest
rate is determined by adding this index to a set margin (which is determined by
the lender). Although there are a variety of adjustable rate mortgage programs
available, the most common program is the One Year Adjustable Mortgage (one Year
ARM). The interest rate on the one year ARM is adjusted once each Year, for 30
years. APR's on variable rate loans are subject to increase but may decrease
from year-to-year, the borrower should be prepared to handle an increase in
his/her monthly payment (should the index rate increase).