Interest-Only Mortgage Term Extension: How It Works
An interest-only mortgage term extension moves your mortgage end date later, giving you more time to repay the capital. It does not reduce what you owe. Lenders may agree if you pass their age and affordability checks and can show a credible plan to repay the loan by the new end date.
This guide explains what lenders look at, what the extra years cost and the alternatives. It is general information, not financial advice.
What an interest-only mortgage term extension does
Extending the term pushes the final repayment date further into the future, for example from age 70 to 75. Monthly payments usually stay similar, because the balance is unchanged. At the new end date, the full capital is still outstanding.
This is different from switching to a repayment mortgage, where monthly payments rise but the balance falls over time.
When lenders may agree to an extension
Extensions are not automatic. Lenders usually look at three things.
Your age at the new end date
Most lenders set a maximum age at the end of the term, and this varies widely between lenders, so check each lender's criteria. Retirement interest-only mortgages work differently: they have no fixed end date, and many RIO lenders set no maximum age.
Affordability
The lender will want to see that you can keep paying the interest for the longer term. If the term runs into retirement, it will usually assess your expected pension income.
Evidence of a repayment plan
This is often the deciding factor. Lenders usually want documented evidence of how the capital will be repaid, such as:
- A pension lump sum due by a set date, shown on a pension statement.
- A maturing investment or endowment, with its latest projection. If an endowment is expected to fall short, see our guide to endowment shortfalls.
- A planned sale of your home or another property, with a recent valuation and enough equity left for your next home.
A general intention to "sort it out later" is unlikely to be accepted.
The cost of paying interest for longer
Because the balance does not fall, every extra year adds a full year of interest. As an illustration, on a £100,000 interest-only balance at an assumed rate of 5% a year, interest is about £5,000 a year, or roughly £417 a month. A five-year extension would add around £25,000 in interest, and the £100,000 would still be owed at the end.
Your rate may also change if you move onto a new product, so it is worth asking for the costs in writing.
Short-term support from your lender
If payments are difficult, some lenders can offer temporary help, such as switching to interest-only or extending the term for up to six months, with the option to switch back within that period.
Alternatives to a term extension
If an extension is not offered, or would only delay the problem, other routes include:
- Using savings or a pension lump sum. See pension options at 55.
- Downsizing, which can clear the loan but means moving and paying moving costs. See downsizing explained.
- A retirement interest-only (RIO) mortgage, where you pay interest monthly and the loan is usually repaid when the home is sold after you die or move into long-term care. Our guide to retirement interest-only mortgages explains how they work, and the RIO affordability calculator gives an indicative idea of what you may be able to borrow.
- Equity release for homeowners aged 55+, which usually has no monthly payments, but interest builds up and reduces the value of your estate. See our equity release guide.
Our guide to options when an interest-only mortgage is ending compares the benefits and drawbacks of each.
Not sure where to start?
Contacting your lender as early as you can, well before your end date, usually leaves more options open.
An FCA-regulated mortgage adviser can look at your whole situation, including whether an extension or another route may fit. We do not provide financial advice.
Not sure which option fits your circumstances?
Written and reviewed by the Later Life editorial team. Last updated .
Frequently asked questions
How long can I extend an interest-only mortgage term?
There is no single answer. It depends mainly on your lender's maximum age at the end of the term, whether you can afford the interest for longer, and how convincing your repayment plan is. Your lender or an FCA-regulated mortgage adviser can tell you what may be possible in your case.
Will extending the term change my monthly payments?
On an interest-only basis, monthly payments usually stay similar, because you are still paying interest on the same balance. They can change if your interest rate changes, for example when a fixed deal ends or the lender moves you to a new product. Over the whole term you pay more interest, because you are paying it for longer.
Can I extend my mortgage term if I am already retired?
Possibly. Lenders will usually check that the new end date falls within their age limits and that your pension and other income can cover the interest. If a standard extension is not available, a retirement interest-only (RIO) mortgage is one alternative some homeowners look at, as it usually has no fixed end date.
What can I do if my lender refuses a term extension?
You can ask the lender to explain its decision and what other options it can offer. If you think you have been treated unfairly, you can complain to the lender and then, if needed, to the Financial Ombudsman Service, which is free. Other routes, such as switching to repayment or downsizing, are covered in our guide to interest-only mortgage ending options.
Is a term extension the same as a retirement interest-only mortgage?
No. A term extension keeps your existing mortgage but moves the end date, so the capital still has to be repaid on a set date. A retirement interest-only (RIO) mortgage is a separate product where you pay interest monthly and the loan is usually repaid when the home is sold after you die or move into long-term care.