Interest-Only Mortgages: Lower Payments, Bigger Questions
Monthly payments can be hundreds less than a repayment mortgage — but you still owe the full balance at the end. Here’s what you need to know.
Ersan
Director
An interest-only mortgage is a type of home loan where your monthly payments cover only the interest charged on the amount you have borrowed. Unlike a standard repayment mortgage, none of your monthly payment goes towards reducing the capital balance, which means you still owe the full original loan amount at the end of the term. For this reason, lenders require you to have a credible repayment strategy in place before they will approve the mortgage.
Interest-only deals were once the default choice for millions of UK borrowers, but lending criteria have tightened considerably since the 2008 financial crisis. Today, most residential interest-only mortgages require a minimum income of around £75,000 (sometimes higher), a deposit of at least 25%, and evidence of a realistic plan to repay the capital at the end of the term. The picture is different for buy-to-let investors, where interest-only remains the most common mortgage structure because the property itself is usually the repayment vehicle.
In this guide we explain exactly how interest-only mortgages work, who qualifies, how they compare to repayment mortgages, the repayment strategies lenders accept, the advantages and risks, and what to do if you already have an interest-only mortgage and want to switch. Whether you are considering an interest-only deal for the first time or reviewing your existing arrangement, this guide will help you understand your options and make an informed decision.
What is an interest-only mortgage?
With an interest-only mortgage, your monthly payment covers the interest your lender charges on the outstanding loan and nothing more. The capital balance — the amount you originally borrowed — stays the same throughout the entire mortgage term. At the end of the term, you must repay the full capital in one lump sum.
Because the capital is never reduced, you need a separate plan — known as a repayment vehicle — to accumulate enough money to clear the debt when the mortgage matures. Lenders will ask for evidence of this plan at the application stage and may review it periodically during the term. Understanding how different mortgage rates affect your monthly interest cost is essential when evaluating this type of deal.
Interest-only vs repayment: £300,000 mortgage at 4.5% over 25 years
£1,125
Interest-only monthly payment
Covers interest only — capital stays at £300,000
£1,667
Repayment monthly payment
Covers interest plus capital — loan cleared by end of term
£542
Monthly difference
Lower payment, but you must save this elsewhere to repay the capital
£300,000
Lump sum due at end of term
The full capital balance must be repaid when the mortgage matures
Your capital never reduces
Unlike a repayment mortgage where every monthly payment chips away at the balance, an interest-only mortgage leaves you owing the same amount in year 25 as you did in year one. You must have a credible strategy to repay this lump sum.
Who qualifies for an interest-only mortgage?
Residential interest-only mortgages are no longer widely available to all borrowers. Following the Mortgage Market Review in 2014, the FCA tightened the rules around affordability and repayment strategies, and most high-street lenders now reserve interest-only deals for higher-income applicants with substantial deposits.
The rules are different for buy-to-let mortgages. Most BTL lenders offer interest-only as standard because the property itself is expected to be the repayment vehicle. Our buy-to-let guide explains the specific criteria in more detail.
Minimum income requirement
- Most lenders require a household income of at least £75,000 to £100,000 for residential interest-only. Some specialist lenders may have different thresholds.
Higher deposit needed
- Expect to need at least a 25% deposit (75% LTV maximum). Some lenders require even more. Check your position with our [borrowing calculator](/calculators/borrow-amount).
Repayment strategy required
- You must demonstrate a credible plan to repay the capital at the end of the term. Lenders will assess your strategy at application and may review it periodically.
Buy-to-let is different
- Interest-only is standard for BTL mortgages. The property sale or portfolio refinancing is usually accepted as the repayment strategy.
Interest-only vs repayment: how they compare
The fundamental difference between these two mortgage types comes down to what your monthly payment actually covers. With a repayment mortgage, each payment includes both interest and a portion of the capital, so the loan is gradually paid off over the term. With interest-only, your payment covers just the interest, and the capital remains untouched. Use our repayment calculator to see the exact figures for your situation.
£250,000 mortgage at 4.5% over 25 years
Repayment mortgage
- Monthly payment: £1,389
- Total interest paid: £166,700
- Balance at end of term: £0
- No lump sum needed
- Equity builds every month
Interest-only mortgage
- Monthly payment: £938
- Total interest paid: £281,250
- Balance at end of term: £250,000
- Lump sum of £250,000 required
- No equity built through payments
“The monthly saving on interest-only can be substantial, but the total cost of the mortgage is often far higher because you pay interest on the full balance for the entire term. Over 25 years, the difference in total interest on a £250,000 mortgage can exceed £114,000.”
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Repayment strategies lenders accept
When you apply for an interest-only mortgage, your lender will want to see a realistic plan for how you intend to repay the capital at the end of the term. Lenders now require specific, documented evidence of your chosen strategy. If you are unsure about how much you can borrow, a broker can assess your options before you apply.
Combine strategies for a stronger application
Many lenders accept a combination of repayment vehicles. For example, you might use a pension lump sum to cover part of the capital and an ISA portfolio for the rest. A mortgage broker can help you structure your application to meet lender requirements. [Get in touch](/contact) to discuss your options.
Advantages and risks of interest-only mortgages
Interest-only mortgages are neither inherently good nor bad — their suitability depends entirely on your financial situation, discipline, and long-term plans. The lower monthly payments can be a genuine advantage for certain borrowers, particularly those with irregular income or those who can invest the difference productively. For buy-to-let investors, interest-only payments maximise rental yield and the interest is tax-deductible.
Weighing up interest-only
Advantages
- Significantly lower monthly payments than repayment
- Greater cash flow flexibility for investing elsewhere
- Ideal for buy-to-let investors (interest is tax-deductible)
- Useful for high earners with lumpy or variable income
- Frees up capital for home improvements or other investments
Risks
- Capital balance never reduces — you owe the full amount at the end
- Total interest paid over the term is substantially higher
- Repayment strategy may underperform (investments can fall in value)
- Stricter eligibility criteria limit who can apply
- Risk of negative equity if property values fall
- You may struggle to remortgage in later life if still on interest-only
Repayment Calculator
Compare your monthly payments on interest-only versus repayment to see the exact difference and total cost over the full term.
Overpayment Calculator
See how making voluntary overpayments on an interest-only mortgage could reduce your capital balance and total interest cost.
Borrowing Calculator
Find out how much you could borrow on an interest-only basis given your income and deposit.
Switching from interest-only to repayment
Many borrowers who started on an interest-only mortgage eventually decide to switch to a repayment basis. This might be because their circumstances have changed, their repayment strategy has underperformed, or they want the security of knowing the mortgage will be fully cleared by the end of the term. Our guide to switching from interest-only covers the process in detail.
You can switch by asking your current lender to change your mortgage to repayment (often a simple administrative change), or you can remortgage to a new lender on a repayment basis. If you remortgage, you have the opportunity to shop the whole market for a better rate at the same time.
Impact of switching: £200,000 balance at 4.5%
£750
Interest-only payment
Current monthly cost covering interest only
£1,111
Repayment (25 years left)
Monthly cost if you switch with 25 years remaining
£1,267
Repayment (20 years left)
Monthly cost if you switch with 20 years remaining
£2,067
Repayment (10 years left)
Monthly cost if you switch with only 10 years remaining
The sooner you switch, the less it costs
Switching from interest-only to repayment with 25 years left adds around £361 to your monthly payment. Wait until you have only 10 years left and the increase is over £1,300 per month. If you are considering a switch, speaking to an adviser sooner rather than later gives you the most options. Use our [overpayment calculator](/calculators/overpayment) to explore how even partial overpayments can reduce your balance.
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“Clearview made the whole mortgage process so much less stressful. Ali explained every step, found us a rate we didn’t think was possible, and kept us updated throughout. We completed in just five weeks.”
Sarah Mitchell
First-Time Buyer
“We were on our lender’s SVR paying way too much. Clearview found us a fixed deal that saved us over £300 a month. The whole switch was handled for us — couldn’t recommend them enough.”
James & Priya Patel
Remortgage
“As a contractor I’d been turned down twice before. Clearview knew exactly which lenders to approach and how to present my income. Got approved first time with a great rate. Absolute lifesavers.”
David Thompson
Self-Employed
“I’ve used Clearview for three BTL purchases now. They understand the portfolio landlord criteria inside out and always find competitive products. Professional, fast, and genuinely knowledgeable.”
Emma Collins
Buy-to-Let Investor
“Selling and buying at the same time felt overwhelming, but Clearview coordinated everything with our solicitor and estate agent. They even helped us port our existing deal. Brilliant service from start to finish.”
Michael & Laura Reed
Moving Home
“I had a CCJ from years ago and thought I’d never get a mortgage. Clearview matched me with a specialist lender and I’m now a homeowner. They treated me with respect and never judged my situation.”
Rachel Okonkwo
Bad Credit Mortgage
“Clearview made the whole mortgage process so much less stressful. Ali explained every step, found us a rate we didn’t think was possible, and kept us updated throughout. We completed in just five weeks.”
Sarah Mitchell
First-Time Buyer
“We were on our lender’s SVR paying way too much. Clearview found us a fixed deal that saved us over £300 a month. The whole switch was handled for us — couldn’t recommend them enough.”
James & Priya Patel
Remortgage
“As a contractor I’d been turned down twice before. Clearview knew exactly which lenders to approach and how to present my income. Got approved first time with a great rate. Absolute lifesavers.”
David Thompson
Self-Employed
“I’ve used Clearview for three BTL purchases now. They understand the portfolio landlord criteria inside out and always find competitive products. Professional, fast, and genuinely knowledgeable.”
Emma Collins
Buy-to-Let Investor
“Selling and buying at the same time felt overwhelming, but Clearview coordinated everything with our solicitor and estate agent. They even helped us port our existing deal. Brilliant service from start to finish.”
Michael & Laura Reed
Moving Home
“I had a CCJ from years ago and thought I’d never get a mortgage. Clearview matched me with a specialist lender and I’m now a homeowner. They treated me with respect and never judged my situation.”
Rachel Okonkwo
Bad Credit Mortgage
“Clearview made the whole mortgage process so much less stressful. Ali explained every step, found us a rate we didn’t think was possible, and kept us updated throughout. We completed in just five weeks.”
Sarah Mitchell
First-Time Buyer
“We were on our lender’s SVR paying way too much. Clearview found us a fixed deal that saved us over £300 a month. The whole switch was handled for us — couldn’t recommend them enough.”
James & Priya Patel
Remortgage
“As a contractor I’d been turned down twice before. Clearview knew exactly which lenders to approach and how to present my income. Got approved first time with a great rate. Absolute lifesavers.”
David Thompson
Self-Employed
“I’ve used Clearview for three BTL purchases now. They understand the portfolio landlord criteria inside out and always find competitive products. Professional, fast, and genuinely knowledgeable.”
Emma Collins
Buy-to-Let Investor
“Selling and buying at the same time felt overwhelming, but Clearview coordinated everything with our solicitor and estate agent. They even helped us port our existing deal. Brilliant service from start to finish.”
Michael & Laura Reed
Moving Home
“I had a CCJ from years ago and thought I’d never get a mortgage. Clearview matched me with a specialist lender and I’m now a homeowner. They treated me with respect and never judged my situation.”
Rachel Okonkwo
Bad Credit Mortgage
Your next steps
Continue Your Mortgage Journey
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Understand Interest-Only
You’re here — learn how interest-only mortgages work, who qualifies, and what repayment strategies lenders accept.
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Compare the Numbers
Use our repayment calculator to see the exact monthly and total cost difference between interest-only and repayment.
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Check What You Can Borrow
Find out how much lenders will offer you on an interest-only basis given your income, deposit, and repayment strategy.
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Get Expert Advice
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