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How a 5/1 ARM Interest Only Mortgage Works

Mark Cappel
UpdatedJun 12, 2024

Please explain what a 5/1 ARM Interest only loan is.

Please explain what a 5/1 ARM Interest only loan is.

Thanks for visiting The loan you are describing is a type of Adjustable Rate Mortgage ("ARM") frequently called a “hybrid ARM” because it combines aspects of both the classic fixed rate and adjustable rate mortgages.

The interest rate on a hybrid ARM is "fixed" for the first few years of the mortgage. After the fixed rate period ends, the interest rate begins to adjust at a defined interval, just like a regular ARM.

Different types of hybrid loans are named based on the number of years for which the interest rate is fixed, represented by the first number, and how often the rate adjusts thereafter, represented by the second number. For example, in a 5/1 ARM, the 5 means that the interest rate will not change for the first five years of the loan. The 1 (meaning 1 year) tells how often the rate will adjust after five year fixed rate ends. So in a 5/1 ARM, after the five year fixed rate period ends, you can expect your rate to adjust once annually.

Be careful, though, because this numbering system is not always consistent. For example, a 3/6 ARM means that after three years, the loan will adjust every six months, not every six years.

With hybrid ARMs, an interest only (or "IO") option usually means that during the fixed rate period of your loan, your required monthly payments will only cover the monthly interest on the loan. However, after the fixed rate period ends, you will be required to pay a normal “interest + principal” payment. This change in the payment requirements, combined with the fact that your interest rate will likely increase due to the scheduled adjustments, means that your monthly mortgage payment may increase significantly. This can be source of significant "payment shock" which means that your monthly payment could skyrocket after the teaser period expires (5 years in your case).

Interest only hybrid ARMs may work for borrowers expecting significant income growth during the fixed rate portion of their loan. However, many borrowers take this type of mortgage because of the initial low monthly payments, but they are unprepared when their payments drastically increase. When this happens, many people are either forced to sell their homes, sometimes at a loss, or face foreclosure because they cannot afford their mortgage payments.

Before agreeing to any mortgage loan, make sure you discuss the terms in detail with the lender or broker. Also, make sure that you carefully read the mortgage agreement to verify that the terms outlined in the contract match the terms that you and the lender discussed. The last thing you want is to be stuck in a mortgage which you cannot afford due to a misunderstanding of the terms of the loan.

If you are buying a new home, I encourage you to explore the Home Purchase page for more information about buying and financing a home.

I would also strongly encourage you to compare rates and offers from multiple lenders. You can apply with Bills approved lender network, and see if you can get a better deal!

I hope this information helps you Find. Learn. Save!

Good Luck,


The Latest on Mortgage Rates

Mortgage rate fluctuations should come as no surprise. If you are buying a home or refinancing your existing mortgage, it is important to stay informed about the current mortgage rates.

Mortgage rates April 10, 2024
According to Freddie Mac, the 30-year mortgage rate for the week of April 10, 2024 is 6.88%. This represents a 6 basis points increase from the previous week's rate.
Note: A basis point is equal to one-hundredth of one percent (0.01%). In numerical terms, if the mortgage rate changes by 20 basis points, it means the rate has changed by 0.20%.
According to Freddie Mac, the 15-year mortgage rate for April 10, 2024 is 6.16%. This is a 10 basis points increase from last week’s rates.

What does the mortgage rate mean for you?
Mortgage rates play a vital role in determining your monthly payment. Let's take a look at the avergage interest rates (APR) for April 14, 2024 based on Zillow data for borrowers with a high credit score (680-740) in the United States:

  • For a 30-year conventional loan, the interest rate is 7.09%.
  • If you opt for a 15-year conventional loan, the interest rate stands at 6.29%.
    Using the rates mentioned above, a $279,082 30-year-year mortgage would result in a monthly payment of $1,874. On the other hand, a 15-year mortgage would require a monthly payment of approximately $2,399.

Experience a smooth mortgage process: Shop around and get pre-approved today!
Shopping around for mortgages and getting pre-approved can make your home-buying or refinancing process easier. Ready to take the plunge? Check Out mortgage rates now for the best options available.



jjohnthomas, Nov, 2010
I am very pleased with the thought and do not feel like adding anything in it. It a perfect answer.Excellent site, keep up the good work. I read a lot of blogs on a daily basis and for the most part, people lack substance but, I just wanted to make a quick comment to say I am glad I found your blog. Thanks
BBill, Oct, 2007
If you bought a home with 100% mortgage financing, you are not required to wait for equity to build in the home before refinancing your current mortgage. Just because you have a 5/1 mortgage -- you are not technically precluded from refinancing at any time. BUT - consider your equity position and any prepay penalty.Most home owners do wait until they have some equity in their homes before refinancing, as obtaining a 100% refinance loan can be more difficult than qualifying for 100% financing at the time of purchase. When making loan decisions, one of the most important factors potential lenders review is the loan-to-value ratio, or LTV, of the proposed loan. This ratio compares the amount of the loan you are trying to obtain to the current value of your home. The interest rates charged on 100% loan-to-value refinance loans, such as the one you propose in your question, are generally higher than the rates charged on loans with a with lower loan-to-value ratios (it's intuitive, since they are riskier loans for the lender). However, if your credit score has increased significantly since you first purchased your home (or if your income has risen), you may be able to obtain a lower interest rate despite the fact that you are refinancing at 100% LTV. You should contact several potential lenders to discuss the loan terms they can offer you on a 100% LTV refinance loan. After speaking with several lenders, you should be able to determine whether or not a refinance loan is a financially viable option for you. If you want an introduction to pre-screened mortgage lenders, makes it easy to compare mortgage offers and different loan types. Please visit the loan page and find a loan that meets your needs at: Another problem encountered by many borrowers trying to refinance their home loans are early refinance penalties charged by their current lenders. Many loan agreements, especially "sub-prime" loans designed for borrowers with credit problems, state that borrowers must pay a penalty to their current lender if they wish to refinance their loan before the expiration of a certain period defined by the loan agreement. These "penalty periods" vary from loan to loan, but are frequently between two to five years from the date of the original mortgage. Before you attempt to refinance your current mortgage, you should contact your current lender to discuss whether or not your current loan agreement includes a prepayment penalty, and if so, its amount and when you can refinance without penalty. These penalties can be quite costly, and can easily make a refinance loan too expensive to save you money over your previous loan. Again, you should find out the amount of the penalty, if any, on your current loan, then contact several potential refinance lenders to discuss whether or not a refinance loan is a practical solution for you. To learn more about refinance loans, I encourage you to visit the Home Refinance Information page at If you enter your contact information in the Savings Center at the top of the page, we can have several pre-screened lenders contact you to discuss the refinance options available to you. I wish you the best of luck in finding a loan the meets your needs, and hope that the information I have provided helps you Find. Learn. Save.Best,
ssean carroll, Oct, 2007
how long before you can refinance on a 5/1 ARM interest only loan