Interest-Only Mortgage

What is Interest-Only Mortgage?

Interest-only mortgages are a type of loan in which the borrower initially makes payments consisting of just the interest amount for a specified period of time. Once the interest-only period ends, borrowers begin making payments on the principal amount as well or choose to refinance.

Depending on how the loan is set up, the period of interest-only payment could typically last for the first 5 to 10 years or the whole of the term in some cases.

Interest-Only Mortgage

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Key Takeaways
  • Interest-only mortgages are a type of loan in which the borrowers do not immediately pay back the principal amount and only pay for interests accrued on the borrowed sum for a specified period of time. The interest-only period typically lasts for 5-10 years.
  • Having lower monthly payments in the initial phase (due to just paying interest) buys a homeowner time to arrange for repayment finances.
  • The monthly payments shoot up substantially post the interest-only period, requiring the borrower to pay both principal and interest amounts as happens in a conventional mortgage loan. Some lenders of interest only-mortgage charge higher interest rates post the initial phase.
  • These loans can be useful for some, but since later on, the payment amount goes up, individuals should be financially prepared when going for them.

How Does Interest-Only Mortgages Work?

How to Calculate Interest-Only Mortgages?

The calculations will consist of two parts – during the interest-only phase and after. As the name implies, you will start by only paying the interest amount on loan during the interest-only phase. The interest rate will either be a fixed-rate or an adjustable-rate during that period. In fixed-rate, the payments shouldn’t change.

Many lenders opt for the loan type of adjustable-rate mortgage for an interest-only mortgage. This ensures that they reap higher interest earnings with the changing market conditions. The mortgage structure may change post the interest-only phase depending on the structure of the loan.

Keep in mind that your payments will increase significantly after the initial phase is over without contributing towards the principal redemption during this time. You will have to pay interest on top of the principal that now needs to be paid off in a shorter time. Using a mortgage calculatorMortgage CalculatorA mortgage calculator is used to compute the value of the monthly installment payable by the borrower on the mortgage loan. It considers the loan amount, the annual rate of interest, and the repayment frequency for more, you can determine the monthly payment for the remaining amount.

Interest-only loans are typically structured as ratios. For example, a 7/1 loan ratio means the first seven years will be interest-only, and after that period, the interest rate adjusts once a year. There are plenty of interest-only mortgage calculators worldwide that can help you compute the amount of due interest and principal amount. In the interest-only mortgage calculators, you will need to enter the loan details and the prevailing annual interest rate.


Let’s say you are looking to buy a $250,000 house and afford to put $50,000 down towards it. So, you go to the bank looking for a $200,000 loan. The loan is a 30 year fixed rate, with the first ten years being interest only at an interest rate of 3.2%. This means that for the first ten years, you will be paying $533 a month towards the loan in interest only.

After the first ten years, the monthly payments will go over  $1,200, assuming the same interest rate. That’s more than double the amount you were paying during the initial interest-only period. The significant increase is due to pushing the principal payments back. Some borrowers opt for a lump-sum payment or a balloon paymentBalloon PaymentWhen part repayment of principal loan such as mortgage loan, commercial loan, etc. is agreed to be made at the end of the loan period or at the maturity where the total outflow is higher than the approx. amount payable on the monthly basis since it does not fully amortize over the term of the loan due to its large amount then it is known as balloon more route to repay the whole principal amount in one go. They can save themselves from the hassle of the increased amount of monthly payments post the interest-only phase.

Pros and Cons

There are advantages and disadvantages you should consider with interest-only mortgages. These include:


  • With mortgage payments typically being one of the most significant expenses for many people, going with interest-only loan can help keep payments low. This can allow individuals to pay off debt (student loans, medical expenses, high-interest credit cards) that might need more immediate attention.
  • During the interest-only phase, if your interest rate is low, you can potentially invest the money you would be paying towards the principal in other investments that will yield a higher return in future.
  • Mortgage interest is tax-deductible (for loans less than $750,000), so payments will be deductible during this period.
  • Interest rates are typically low during the initial phase.


  • After the initial interest-only period, your payment will increase significantly, catching some people off guard if they are not prepared at the time.
  • You are also not building equity in the house as you are just paying interest, not contributing towards the principal.
  • Although during the initial period interest rates are low, you will typically encounter higher interest rates afterwards because they become adjustable. Not only will you be paying the principal, but you will most likely have a higher interest rate as well.
  • The value of your home can decline, leaving you owing more money than what the house is worth. This can make things difficult when trying to refinance the mortgage before the initial phase is up.
  • In some instances, the borrower may owe a big lump sum of money once the interest-only period is complete. At times, they require a substantial down payment.
  • Interest-only contracts are often stringent, often dissuading the consumers from taking them, especially with the fear of exploitation. As per a study, allowing more flexibility in the contract led to an increase in the consumption of interest-only financial plans in Denmark.
  • Borrowers must qualify for these types of loans, and in some instances, it may be tough to pass the qualifications: higher credit scores, asset ownership, and a high income to debt ratio.

This has been a guide to what is interest-only Mortgage and its meaning. Here we discuss how to calculate interest-only mortgage and how it works along with Pros & Cons. You may learn more about financing from the following articles –