Quick answer
A repayment mortgage clears your debt in full by the end of the term — monthly payments are higher but you own the property outright at the end. An interest-only mortgage has lower monthly payments but the original loan remains outstanding throughout and must be repaid in a single lump sum when the term ends. For most UK residential buyers, repayment is the right choice. Interest-only suits specific situations — mainly buy-to-let — where there is a clear, credible plan for repaying the capital.
The choice between a repayment and interest-only mortgage is one of the most consequential decisions a UK borrower makes — yet it is often treated as a minor detail in the rush to secure a property. Get it right and you have a mortgage structure that suits your finances and your long-term goals. Get it wrong and you could reach the end of your term still owing the original loan in full, with no obvious way to repay it.
Both types are fundamentally different products. The lower monthly cost of interest-only can look attractive on paper, but the numbers tell a different story once you account for what is owed at the end — and how much total interest you will have paid to get there.
Repayment vs interest only: the key differences
Repayment mortgage
Pay off capital and interest each month
- Monthly payment covers both interest and capital
- Balance reduces every single month
- Debt is fully cleared by end of term
- Higher monthly cost than interest-only
- You build equity in the property throughout
- Available to virtually all residential borrowers
- No requirement for a separate repayment vehicle
Interest-only mortgage
Pay interest each month, capital stays the same
- Monthly payment covers interest only
- Balance does not reduce — stays at original amount
- Full loan must be repaid at end of term
- Lower monthly cost than repayment
- You build no equity unless property value rises
- Harder to access for residential buyers post-2008
- Requires a documented capital repayment plan
How the costs actually compare — the full picture
The monthly saving on interest-only looks meaningful at first glance. But when you add up what you pay over the full term — and account for the capital that still needs repaying — the true cost of interest-only is dramatically higher. The table below uses a £200,000 mortgage at 4.5% as a consistent example.
| Metric | Repayment | Interest only | Difference |
|---|---|---|---|
| Monthly payment (25 yrs) | £1,111 | £750 | £361/month more on repayment |
| Total paid over 25 years | £333,400 | £425,000* | £91,600 more on interest only |
| Total interest paid | £133,400 | £225,000 | £91,600 more on interest only |
| Balance owed at end | £0 | £200,000 | Full capital still outstanding |
| True total cost (inc. capital) | £333,400 | £425,000 | Interest only costs £91,600 more |
*Interest-only total assumes the £200,000 capital is repaid at the end of the term in addition to 25 years of monthly interest payments.
The critical point here is that the £200,000 outstanding at the end of the interest-only term does not appear in your monthly outgoings. It is easy to lose sight of it. But it represents a very real financial obligation — one that, if you cannot meet it, puts your home at risk.
How the monthly payment breaks down over time — repayment
With a repayment mortgage, the proportion of each payment that goes to interest versus capital shifts significantly over the term. In the early years you are mostly paying interest; in the later years mostly capital.
Interest vs capital split — £200,000 repayment mortgage at 4.5%
With interest-only, that bar stays entirely amber for the full 25 years — you are paying interest every single month on the same £200,000 balance, because nothing reduces it.
Real UK scenarios — which type fits which situation
Amara is a 29-year-old buying her first home in Leicester for £195,000 with a 10% deposit, giving her a £175,500 mortgage. She earns £38,000 and has no other significant debts. Her lender quotes 4.55% for a five-year fixed repayment mortgage over 25 years.
Monthly repayment: £973. An interest-only option would cost £666/month — saving £307 per month — but her lender will not offer interest-only to a first-time residential buyer without a documented repayment vehicle, which Amara does not have.
Even if she could access interest-only, the £175,500 still owed at the end of 25 years would require selling the property or finding another way to repay it. On repayment, she will own her home outright at 54.
Derek owns a two-bed flat in Manchester with a £165,000 buy-to-let mortgage at 5.1% interest-only. Monthly interest cost: £702. The property rents for £1,050 per month, generating £348 gross monthly profit before management fees and maintenance.
If Derek switched to repayment over 20 years, his monthly cost would jump to £1,101 — turning a profitable investment into a monthly loss of £51 before other costs. His plan is to hold the property for 15 years and sell it to repay the capital, by which point he expects significant capital appreciation in the Manchester market.
Paul took out a £180,000 interest-only residential mortgage in 2007 at 5.5% over 25 years — a common product at the time. His monthly payment has always been £825. In 2032 the term ends and he still owes the original £180,000. He has no investment vehicle, no pension large enough to cover it, and insufficient equity to downsize after transaction costs.
This is the real-world consequence of interest-only without a repayment strategy. The FCA estimated over 200,000 UK homeowners face a similar situation — often referred to as the "interest-only time bomb."
Who each mortgage type genuinely suits
Repayment mortgage
Right for most UK residential buyers
- First-time buyers with no separate repayment vehicle
- Anyone whose primary goal is to own their home outright
- Borrowers who want predictable, debt-reducing payments
- Those who plan to stay in the property long-term
- Buyers with a standard employment income
- Anyone who wants to build equity steadily over time
Interest-only mortgage
Suitable in specific circumstances only
- Buy-to-let landlords maximising monthly cash flow
- High-net-worth buyers with substantial investment portfolios
- Those with a genuinely credible capital repayment plan
- Short-term owners who plan to sell before term ends
- Borrowers using the saving to overpay another higher-rate debt
- Older borrowers with pension or inheritance repayment vehicles
The risks of interest-only that borrowers underestimate
Important — read before choosing interest only
The single biggest risk is arriving at the end of your term with a large capital sum due and no reliable way to pay it. Lenders can — and do — pursue repossession in this scenario. The FCA has repeatedly warned that hundreds of thousands of UK homeowners on legacy interest-only deals face exactly this situation.
A secondary risk is negative equity. If property prices fall, your outstanding balance could exceed the value of the property, trapping you in a mortgage you cannot exit through sale without crystallising a loss.
Finally, interest-only mortgages carry rate risk at renewal just like repayment deals — but because the balance never reduces, you are always refinancing the original loan amount, meaning rate rises hit your payments harder over a longer period.
The safeguards lenders now apply exist precisely because of the scale of problems that arose when interest-only was widely sold in the 1990s and 2000s without adequate repayment plans. If a lender is asking for a documented repayment vehicle, that requirement protects both parties — not just the lender.
A middle ground: part-and-part mortgages
Some lenders offer a part repayment, part interest-only structure — sometimes called a "part-and-part" mortgage. This splits your loan into two portions: you repay one portion on a capital repayment basis, while the other runs on interest-only terms.
For example, on a £200,000 mortgage you might arrange £130,000 on repayment and £70,000 on interest-only. Your monthly payment is lower than a full repayment deal, but you still reduce your balance meaningfully each month. At the end of the term you still owe the £70,000 interest-only portion — so you still need a repayment plan for that — but the overall risk is substantially lower than full interest-only.
This approach suits borrowers who find full repayment payments stretching their budget uncomfortably, but who want to avoid the full capital-risk exposure of pure interest-only. Use our mortgage calculator to model the repayment portion and understand how the split affects your monthly outgoings.
Common mistakes when choosing between mortgage types
Treating the monthly saving as pure profit
The £361/month saving on interest-only versus repayment on a £200k mortgage is not free money — it comes with a £200,000 liability at the end of the term. That saving only works in your favour if you genuinely invest it in a vehicle that will produce enough to repay the capital. Most people do not.
Relying on property price growth as the repayment plan
UK property prices have historically risen, but they do not always rise in time with your mortgage term — or by enough to cover a loan that has not reduced by a single pound. Using expected capital appreciation as your sole repayment vehicle is speculative, not a plan. Lenders are unlikely to accept it as one.
Not reviewing an interest-only mortgage regularly
If you are on an interest-only deal, your repayment vehicle needs to be reviewed every few years — not set and forgotten. Investment performance changes, circumstances change, and the shortfall between what you have saved and what you owe can grow silently. Annual reviews with a financial adviser keep the end-of-term obligation visible and manageable.
Choosing interest-only simply because the monthly payment is lower
If your reason for choosing interest-only is primarily that repayment feels unaffordable, that is a signal worth paying attention to. It may mean the property is beyond your means at current rates, or that a longer repayment term would achieve the same affordability goal without carrying the capital risk of interest-only.
Frequently asked questions
What is the difference between a repayment and interest-only mortgage?
With a repayment mortgage, each monthly payment reduces your outstanding balance and pays the interest charged that month — the debt is fully cleared by the end of the term. With interest-only, your payment covers only the interest, and the original loan amount stays the same throughout. The full capital must be repaid in a single lump sum when the term ends.
Can I still get an interest-only mortgage in the UK?
Yes, but the criteria are much stricter than they were before 2008. For residential purchases, most lenders require a credible repayment vehicle — such as an investment portfolio, pension, or endowment — and a minimum income or equity level. Interest-only remains widely available for buy-to-let mortgages, where the expected property sale is a more straightforward repayment plan.
Is interest only cheaper than repayment?
Month to month, yes. On a £200,000 mortgage at 4.5% over 25 years, interest-only costs £750/month versus £1,111 on repayment. But over 25 years you will have paid £225,000 in interest on interest-only versus £133,400 on repayment — and still owe the original £200,000. The total true cost of interest-only is £91,600 more.
Who should consider an interest-only mortgage?
Interest-only is genuinely suitable for buy-to-let landlords with positive cash flow and a clear exit plan, high-net-worth residential buyers with documented repayment vehicles, and those in specific circumstances where the capital will definitely be available at the end of the term. It is rarely suitable for standard residential buyers — particularly first-time buyers — without a robust, concrete repayment strategy.
What happens at the end of an interest-only mortgage?
The full original loan becomes due in one lump sum. If you cannot repay it through your chosen vehicle — property sale, investments, pension, or refinancing — the lender can take possession of the property. This is why lenders now require a documented repayment plan upfront, and why reviewing that plan regularly throughout the term is essential.
Related calculators and guides
Calculator
Mortgage calculator UK
Compare repayment and interest-only monthly costs side by side.
Guide
£200k mortgage monthly payment
See exact repayment figures used in the examples on this page.
Guide
Should I overpay my mortgage?
Once you are on repayment, find out whether overpaying makes financial sense.
DisclaimerThis article is for informational purposes only and does not constitute financial or mortgage advice. Mortgage eligibility, product availability, and interest rates change regularly. Always seek advice from a qualified, FCA-regulated mortgage adviser before deciding on a mortgage type.
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✓ Editorially reviewed — all Poqet guides are checked for factual accuracy before publication and updated when UK rates or legislation change. Editorial Policy