Adjustable Rate Mortgage

ARM Loan

7 year ARM, 5 year ARM, 3 year ARM, 1 year ARM, 7/1, 5/1, 3/1, 1/1

An adjustable rate mortgage (ARM) is a loan with an interest rate that can be adjusted at pre-set intervals. The amount of the adjustment depends on several factors outlined below. Some ARM loans have an initial period where the interest rate is fixed for a period of time like 2, 3, 5, 7, or 10 years. After the fixed period the loan converts to an adjustable rate mortgage. Some ARM loans are adjustable during the first year with the adjustment beginning after 1, 3, 6, or 12 months. Usually there is a cap on the rate which determines the highest rate could pay. ARM loans adjust based on the following factors:

  1. Index:
    The index of an ARM is the financial medium that the interest rate is based upon. The most familiar indices, or indexes, are the 1-Year Treasury, 6-Month Certificate of Deposit (CD), Prime, COFI (the 11th District Cost of Funds) and LIBOR (London Interbank Offered Rate). Each of these indices move up or down based on fluctuations in the financial market.
  2. Margin:
    The margin is one of the most significant aspects of ARM’s because it is added to the index to determine the interest rate that you pay. The margin added to the index is known as the fully indexed rate. As an example if the current index rate is .07% and your loan has a margin of 2.0%, your fully indexed rate is 2.07%. Margins on loans range from 1.75% to 3.5% depending on the index and the amount of the loan.
  3. Payment Caps:
    Several loans programs have payment caps as a substitute to interest rate caps. These loan programs diminish payment shock in a market with rising interest rates, but can also lead to deferred interest or negative amortization. Such loans normally cap your annual payment increases to 7.5% of the previous payment.
  4. Interim Caps:
    This limits how the interest rate can be changed each time it is adjusted. The cap is usually between 1% and 2%.
  5. Lifetime Caps:
    Practically all ARMs have a maximum interest rate or lifetime interest rate cap. However, the limit of lifetime cap varies within each company and different loan programs. Loans with low lifetime caps usually have higher margins.


  • ARM’s allow you to have the lowest interest rate and lower monthly payment for a short period.
  • You have the option to refinance if interest rates drop.
  • Rates and payments may go down if rates improve.
  • It is a great program if you plan to sell the house in a few years.
  • You may qualify for a higher loan amount.


  • After the initial fixed rate term is over the ARM period could cause your rate and payment to increase.
  • If the ARM increases after the initial fixed period you might need to refinance at a higher rate.
  • Payments may increase over time.