How to Switch from a Repayment Mortgage to Interest-Only in the UK and What It Really Costs
When the Monthly Bills Feel Impossible: Is Interest-Only the Answer?
If you’re lying awake wondering how you’re going to cover your mortgage this month, you’re not alone. With the cost of living still biting hard in 2026, a growing number of UK homeowners are asking their lender the same question: can I switch to interest-only to bring my payments down? The short answer is yes — sometimes. But the full answer is far more complicated, and the long-term cost can be eye-watering if you go in without understanding what you’re agreeing to.
This article walks you through exactly how the switch works, what lenders will demand from you, how much it genuinely costs over time, and what pitfalls to watch for.
What Switching to Interest-Only Actually Means
On a standard repayment mortgage, each monthly payment covers two things: the interest the lender charges, and a slice of the capital (the actual loan amount). Over 25 years, you gradually pay the whole thing off.
On an interest-only mortgage, your monthly payment covers only the interest. The original loan — every penny of it — is still sitting there at the end of the term. You are responsible for repaying it in full, usually through what lenders call a repayment vehicle (more on that shortly).
Example: On a £200,000 mortgage at 5.5% interest over 25 years, a repayment mortgage costs roughly £1,227/month. The same mortgage on interest-only? Around £917/month — a saving of about £310 per month. But at the end of 25 years, you still owe £200,000.
That difference feels like breathing room when you’re financially stretched. But it is not free money — it is deferred debt.
Can You Actually Switch? Lender Eligibility Requirements
Since the Mortgage Market Review in 2014 and ongoing FCA regulation, lenders are far more cautious about interest-only than they once were. If you’re hoping to switch, here is what most major UK lenders — including Nationwide, Halifax, Barclays, and NatWest — will typically require:
- A credible repayment strategy. You must demonstrate how you will repay the capital at the end of the term. Acceptable vehicles usually include an ISA, pension, endowment, or the planned sale of another property. “I’ll sell the house” is sometimes accepted, but increasingly scrutinised.
- Sufficient equity. Most lenders require a minimum of 25–50% equity in your property before they’ll allow interest-only. If you’re in negative equity, this route is essentially closed to you.
- Affordability assessment. Even though the monthly payment is lower, lenders still run full affordability checks. Your income, outgoings, and credit history all matter.
- Minimum loan size. Some lenders set a minimum loan value — often £150,000 — for interest-only products.
If you are switching within your existing lender (a product transfer rather than a full remortgage), the process is simpler, but the eligibility criteria still apply. Switching to a new lender on interest-only requires a full remortgage application.
The Real Long-Term Cost: Running the Numbers
This is where many people get a nasty shock. Let’s return to that £200,000 mortgage at 5.5%:
| Repayment | Interest-Only | |
|---|---|---|
| Monthly payment | ~£1,227 | ~£917 |
| Total paid over 25 years | ~£368,100 | ~£275,100 in interest + £200,000 capital = £475,100 |
| Difference | — | ~£107,000 more |
Switching to interest-only saves you money monthly, but costs you significantly more overall — and that’s assuming interest rates stay flat, which they rarely do.
Temporary Switches: A Safer Middle Ground
The good news is that you don’t have to commit to interest-only for the rest of your mortgage term. Under FCA guidelines, lenders are required to treat customers in financial difficulty fairly and flexibly. Many will allow a temporary switch — sometimes for six to twelve months — as a short-term forbearance measure.
This is worth asking about directly. Contact your lender, explain your circumstances honestly, and ask specifically about:
- A temporary switch to interest-only
- A payment holiday (though these affect your credit file)
- A term extension (which also reduces monthly payments without the capital risk)
Tip: Before contacting your lender, speak to a free debt adviser. MoneyHelper (moneyhelper.org.uk) offers free, impartial guidance and can help you prepare for the conversation. The National Debtline is another excellent resource.
Common Pitfalls to Avoid
1. Assuming the house will always bail you out. Relying on property price growth to repay your capital is a gamble. UK house prices do generally rise over time, but they also fall — as 2023 demonstrated. If values drop and you’ve been on interest-only, you could face negative equity with no capital buffer.
2. Forgetting to set up a repayment vehicle. Lenders ask about your repayment plan at the outset, but they don’t always monitor it rigorously. It’s easy to let an ISA or pension contribution slip — and then find yourself at the end of the term with £200,000 still outstanding.
3. Not reviewing your situation regularly. If you switch temporarily, set a reminder to review at 6 and 12 months. Financial situations change, and reverting to a repayment mortgage as soon as you’re able will save you money long-term.
4. Missing the impact on remortgaging later. Being on interest-only can complicate future remortgage applications, particularly if your equity hasn’t grown because you haven’t been reducing the capital.
When It Might Actually Be the Right Call
There are genuine scenarios where a temporary switch to interest-only makes sound financial sense:
- You’ve experienced a sudden loss of income (redundancy, illness, maternity leave)
- You’re managing short-term debt and need breathing room to clear high-interest balances first
- You’re a landlord on a buy-to-let mortgage, where interest-only is standard practice and the investment rationale is different
The key word is temporary. Used as a short-term tool with a clear plan, interest-only can prevent you from missing payments — which would damage your credit file and potentially risk your home. Used indefinitely without a repayment strategy, it is a slow-building financial problem.
Getting Proper Help
If you’re seriously considering this switch, please speak to a whole-of-market mortgage broker who is authorised and regulated by the Financial Conduct Authority (FCA). You can check any adviser’s registration on the FCA Register at register.fca.org.uk. A good broker will assess your full situation and may find solutions you haven’t considered — including lenders with more flexible criteria.
Free support is also available through: - MoneyHelper — 0800 138 7777 - Citizens Advice — citizensadvice.org.uk - StepChange Debt Charity — stepchange.org
You don’t have to navigate this alone, and asking for help early — before you miss a payment — gives you far more options.
This article is for informational purposes only and does not constitute regulated financial advice. Always seek guidance from an FCA-authorised adviser before making changes to your mortgage.