A guide to interest-only mortgages (UK home buyers)

A guide to interest-only mortgages

An interest-only mortgage is a type of home loan where your monthly payments are calculated to cover only the interest charged on the amount borrowed. In other words, during the mortgage term you are not reducing the capital (the original loan balance).

That means the loan balance is generally still there at the end of the agreed term, so you need a repayment plan to clear what you borrowed. For many borrowers, the decision is less about the monthly payment and more about whether the end-of-term plan is realistic.

In this guide

• What an interest-only mortgage is
• How repayment works
• Common repayment vehicles lenders may consider
• Pros and cons
• When interest-only mortgages may be available
• Retirement interest-only mortgages (RIO)
• Paying off early and managing the mortgage
• Key things to consider before choosing one

What is an interest-only mortgage?

With an interest-only mortgage, each month you typically pay:

• Interest on the outstanding loan balance
• No repayment of the capital

Because the capital doesn’t reduce, the mortgage balance you owe at the end of the term is generally the same as the amount you borrowed (subject to any changes from overpayments, product features, or other mortgage terms).

A simple example

If you borrow £200,000 and the interest charged is 5% per year, the annual interest is £10,000. Spread across 12 months, that’s roughly £833 per month in interest.

With an interest-only mortgage, your monthly payment would be based on that interest figure, while the £200,000 capital remains to be repaid at the end of the term.

Illustrative example only—your actual payment depends on the interest rate and the mortgage terms.

How do you repay an interest-only mortgage?

The defining feature of an interest-only mortgage is that you must have a repayment plan for the capital at the end of the term.

In practice, repayment strategies usually fall into a few broad categories:

1. Savings or investments built up over time
2. A plan connected to the property (for example, selling)
3. Remortgaging at or near the end of the term

Lenders typically want to understand that the plan is appropriate for the mortgage term and that you can meet the ongoing interest payments as they fall due.

Repayment vehicles: what lenders may look for

A repayment vehicle is the method you intend to use to repay the capital balance. Different lenders may have different views on what they will accept, but common examples include:

• Cash savings (including where relevant, tax-efficient savings wrappers)
• Stocks and shares investments intended to grow over the mortgage term
• Pension savings (where structured appropriately)
• Selling the property to clear the mortgage balance
• Other asset strategies designed to provide the expected lump sum

Why the repayment vehicle matters

Interest-only mortgages shift more of the uncertainty onto the borrower. If the repayment vehicle does not perform as expected, the capital still needs to be covered at the end of the term.

That’s why it’s important to consider:

• whether your plan could be affected by market downturns
• whether you can continue funding the strategy if your circumstances change
• what you would do if you cannot repay the full amount as planned

Pros and cons of interest-only mortgages

Interest-only mortgages can be suitable for some borrowers, but they come with trade-offs.

Potential advantages

• Lower monthly payments compared with a repayment mortgage (because you’re not paying down capital)
• The ability to direct money into a separate repayment strategy
• Potential fit where you have a time-based end point (for example, an expected asset event)

Key disadvantages and risks

• Capital risk: you may still owe the full amount borrowed at the end of the term
• Vehicle risk: savings or investments may not reach the target value
• Total cost risk: paying interest without reducing capital can mean higher overall costs over the life of the mortgage compared with repayment alternatives
• Complexity: you’re effectively managing two elements—the interest payments and the repayment plan

Can you still get interest-only mortgages?

Interest-only mortgages exist in the UK, but they are generally treated as higher risk than standard repayment mortgages because the lender’s exposure depends more on the borrower’s end-of-term plan.

As a result, lenders commonly focus on:

• whether you can afford the interest payments throughout the term
• whether the repayment strategy is suitable and realistic for the mortgage length
• whether the overall mortgage structure fits your circumstances and intended outcome

Because requirements vary, the availability of interest-only options can depend on factors such as the loan size, property type, and the strength of the repayment plan.

Retirement interest-only mortgages (RIO)

A retirement interest-only mortgage is designed for older borrowers and works on similar principles to other interest-only mortgages: monthly payments typically cover interest only.

The capital is usually intended to be repaid when a triggering event occurs, such as:

• the borrower’s death, or
• moving into long-term care

RIO products can be structured differently from standard interest-only mortgages, so it’s important to understand how repayment is expected to happen and what the implications are for the property and your estate.

Paying off an interest-only mortgage early

In many cases, it is possible to repay an interest-only mortgage early. However, whether there are extra costs depends on the mortgage terms.

Early repayment charges

If your mortgage is on a fixed rate, there may be an early repayment charge if you redeem or repay the mortgage during the fixed period.

Overpayments

Some interest-only mortgages allow overpayments, but the effect can vary by product. In some cases, additional payments may reduce the outstanding balance (which can reduce future interest), while in other cases they may be handled differently.

Key things to consider before choosing an interest-only mortgage

Before deciding, it helps to pressure-test both the mortgage and the end-of-term plan.

• Repayment certainty: do you have a realistic way to repay the capital when the term ends?
• Vehicle resilience: how would your plan perform if markets move against you or if interest rates change?
• Affordability over time: can you comfortably meet the interest payments if your income changes?
• Contingency planning: what is your backup if you can’t repay the full amount as expected?
• Total cost comparison: how does the overall cost compare with a repayment mortgage, not just the monthly payment?

Summary

An interest-only mortgage can reduce monthly payments because you pay interest only during the term. The trade-off is that you must have a clear, credible plan to repay the capital at the end of the mortgage.

For many home buyers, the decision comes down to whether the repayment strategy is dependable and whether you’re comfortable with the risks—particularly the possibility that the repayment vehicle may not reach the expected value.