An interest-only mortgage works in a simple way. Each month, you pay only the interest on the loan. You do not pay back the amount you borrowed during the mortgage term.
This means the loan balance stays the same from start to finish. At the end of the term, you must repay the full amount in one payment.
Interest-only mortgages can suit some people, but they are not right for everyone. This guide explains how interest-only mortgage loans work, why people choose them, and what to think about before applying.
What is an interest-only mortgage?
An interest-only mortgage is a loan where your monthly payments cover just the interest charged by the lender. The original loan amount does not go down over time.
For example, if you borrow £200,000, you still owe £200,000 at the end of the mortgage term. Your monthly payments stop the interest from building up, but they do not reduce the loan.
Because of this, you need a clear plan to repay the loan at the end. This is often called a plan to repay.
You can learn more about what an interest only mortgage is and how it compares with other types of mortgage in our glossary.
Why would you have an interest-only mortgage?
People choose interest-only mortgages for different reasons. The most common reason is lower monthly payments.
Because you are not paying back the loan itself, monthly costs are usually lower than with a repayment mortgage. This can help if you want more room in your budget.
Some people choose interest-only mortgages when:
- Their income changes from month to month
- They expect to earn more in the future
- They plan to sell the property later
- They are buying an investment property
Interest-only mortgages are often used for buy-to-let homes. In these cases, rent may cover the interest, and the property sale can repay the loan later.
How do interest-only mortgage loans work?
When you take out an interest-only mortgage, you agree on three main things: the loan amount, the interest rate, and the length of the mortgage.
Each month, you pay the interest charged on the loan. The loan balance does not reduce.
At the end of the term, the full loan must be repaid. This is why lenders usually ask for a clear plan to repay.
Common plans include:
- Selling the property
- Using savings
- Using investments
- Downsizing to a cheaper home
- Using a pension lump sum
Not all lenders accept the same plans. Some lenders are stricter. Others are more flexible and will look at your full situation.
What are the benefits of interest-only mortgages?
Interest-only mortgages can work well in the right situation.
The main benefit is lower monthly payments. This can help with cash flow and day-to-day costs.
They can also offer more choice. Some people start with interest-only payments and switch to repayment later. Others use interest-only to manage changes in income.
Other possible benefits include:
- Lower monthly costs in the short term
- More control over how money is used
- Useful for property investors
- Can support longer-term plans
When used with care and a clear plan, interest-only mortgages can form part of a wider money plan.
What are the disadvantages of interest-only mortgages?
Interest-only mortgages also come with risks.
The biggest risk is that the loan does not reduce over time. You still owe the full amount at the end of the term.
If your plan to repay does not work, you may struggle to clear the loan.
Other risks include:
- House prices can fall
- Savings or investments may underperform
- Life plans can change
- Fewer lenders offer this type of mortgage
In many cases, interest-only mortgages can cost more over time because interest is paid on the full loan for longer.
This is why lenders look at these mortgages carefully.
How do you calculate interest-only payments?
Interest-only payments are based on two things: the loan amount and the interest rate.
For example, if you borrow £200,000 at an interest rate of 5 per cent, the yearly interest is £10,000. That works out at about £833 per month.
A simple way to estimate payments is:
Loan amount × interest rate ÷ 12
If interest rates rise, monthly payments will also rise. This is important to keep in mind when planning your budget.
A lender or mortgage broker can help you check likely payments and see how changes in rates could affect you.
What should I do before applying?
Before applying for an interest-only mortgage, it helps to prepare.
Check what you can afford
Look closely at your income and spending. Make sure you can afford payments now and if rates rise later.
You should also check that your plan to repay the loan is realistic.
Improve your credit score
A good credit record can improve your options. Check your credit report and fix any mistakes. Paying down debts can also help.
Some lenders accept more complex cases, but credit history still matters.
Compare mortgages
Not all lenders offer interest-only mortgages. Those that do may have different rules.
A mortgage broker can help you compare options and find lenders that suit your situation. They can also explain what happens at the end of an interest-only mortgage and help you plan ahead. You can also learn more about can I get an interest-only mortgage and whether it is still available today.
Final thoughts
So, how do interest-only mortgage loans work? You pay only the interest each month, and you repay the full loan later using a clear plan.
Interest-only mortgages can suit some people, especially those who need lower payments or have a strong plan to repay. They are not right for everyone and need careful thought.
Before applying, it is often helpful to speak to a mortgage broker. They can explain how lenders look at interest-only mortgages and whether this type of loan fits your plans.
It’s important to understand that not everyone’s finances are simple. By looking at the full picture, some lenders can offer options that better match how you live and earn.