Trying to decide what type of mortgage is right for you can be tricky business. So you may be wondering what is an adjustable rate mortgage? An adjustable rate mortgage or ARM, has an interest rate that is linked to an economic index. This means the interest rate, and your payments, adjust up or down as the index changes. There are three things to know about adjustable rate mortgages: index, margin and adjustment period. What is the index? The index is a guide that lenders use to measure interest rate changes. Common indexes used by lenders include the activity of one, three, and five-year Treasury securities. Each adjustable rate mortgage is linked to a specific index. The margin is the lender's cost of doing business plus the profit they will make on the loan. The margin is added to the index rate to determine your total interest rate. The adjustment period is the period between potential interest rate adjustments. For example, you may see a loan described as a 5-1. The first figure (5) refers to the initial period of the loan, or how long the rate will stay the same. The second number (1) is the adjustment period. This is how often adjustments can be made to the rate after the initial period has ended. In this case, one year or annually. An adjustable rate mortgage might be a good choice if you are looking to qualify for a larger loan. The rate of an ARM is typically lower than a fixed rate mortgage. Remember, when the adjustment period is up the rate and payment can increase. Another reason to consider an ARM is if you are planning to sell the home within a few years. If this is the case you may end up selling before the adjustment period is up. Federal law provides that all lenders provide a federal Truth in Lending Disclosure Statement before consummating a consumer credit transaction. This will be given to you in writing. It is designed to help you compare and select a mortgage.