Interest-Only vs Repayment Mortgages for Rental Properties
Most buy-to-let mortgages in the UK are taken on interest-only terms, but that doesn't make interest-only right for every investor or every property. The choice changes your monthly cash flow, how much you can borrow, your tax bill and what you owe at the end. Here's how to think about it properly.
The difference in one line
- Interest-only: you pay the interest each month. The loan stays the same and is repaid in full at the end of the term.
- Repayment (capital and interest): you pay the interest plus part of the loan each month. At the end of the term, you owe nothing.
Why most investors choose interest-only
Cash flow
With interest-only, your monthly payment is only the interest. On repayment, a slice of every payment goes towards the loan itself, so the monthly outgoing is noticeably higher on the same loan.
For an investor, that difference is cash flow you can use to cover voids and repairs, build a buffer, or save for the next deposit.
Rental cover
Lenders work out how much you can borrow by comparing the rent to the mortgage interest at a stressed rate. On most buy-to-let products, that calculation is based on interest-only, but repayment loans still have to be affordable month to month. Higher outgoings mean less room if something goes wrong.
Capital growth does the heavy lifting
The investor logic is that property values tend to rise over the long term while an interest-only loan stays flat. A £100,000 loan on a house bought for £133,000 is still £100,000 in 20 years. If the house is worth more by then, your equity has grown without you paying the loan down. [Illustrative figures only]
That's a bet on the long-term market, and it isn't guaranteed. Property values can fall, and have done in the past.
With interest-only, your monthly payment is only the interest. On repayment, a slice of every payment goes towards the loan itself, so the monthly outgoing is noticeably higher on the same loan.
For an investor, that difference is cash flow you can use to cover voids and repairs, build a buffer, or save for the next deposit.
Rental cover
Lenders work out how much you can borrow by comparing the rent to the mortgage interest at a stressed rate. On most buy-to-let products, that calculation is based on interest-only, but repayment loans still have to be affordable month to month. Higher outgoings mean less room if something goes wrong.
Capital growth does the heavy lifting
The investor logic is that property values tend to rise over the long term while an interest-only loan stays flat. A £100,000 loan on a house bought for £133,000 is still £100,000 in 20 years. If the house is worth more by then, your equity has grown without you paying the loan down. [Illustrative figures only]
That's a bet on the long-term market, and it isn't guaranteed. Property values can fall, and have done in the past.
Why some investors choose repayment
Guaranteed equity
Every payment reduces your debt. By the end of the term, the property is yours outright, whatever the market has done.
Lower risk over time
As the loan shrinks, your loan-to-value falls. That makes future refinancing easier and gives you more protection if values dip.
Retirement planning
Investors who want a debt-free income in later life often move some or all properties onto repayment, especially as they get closer to the end of their working life.
Peace of mind
Some investors simply don't want a large balance hanging over them at the end of the term. That's a valid reason.
A shorter term on a strong-yielding property
On a property where the rent comfortably covers a repayment mortgage, some investors shorten the term deliberately so the debt clears faster. Higher yielding markets make this easier than expensive ones, because the rent has more room to absorb the capital element. Run it on your own figures rather than assuming it works.
Every payment reduces your debt. By the end of the term, the property is yours outright, whatever the market has done.
Lower risk over time
As the loan shrinks, your loan-to-value falls. That makes future refinancing easier and gives you more protection if values dip.
Retirement planning
Investors who want a debt-free income in later life often move some or all properties onto repayment, especially as they get closer to the end of their working life.
Peace of mind
Some investors simply don't want a large balance hanging over them at the end of the term. That's a valid reason.
A shorter term on a strong-yielding property
On a property where the rent comfortably covers a repayment mortgage, some investors shorten the term deliberately so the debt clears faster. Higher yielding markets make this easier than expensive ones, because the rent has more room to absorb the capital element. Run it on your own figures rather than assuming it works.
The tax angle
Capital repayments are not a tax-deductible expense, whether you own the property personally or through a company. Only the interest is relevant for tax, and even that is treated differently depending on your structure.
Individual landlords are restricted by Section 24 and receive a basic-rate tax credit on finance costs rather than deducting them. From 6 April 2027, that credit is set at the new 22% property basic rate. Companies deduct interest as a business expense before corporation tax.
This means repayment mortgages reduce your cash flow without reducing your tax bill. Every investor's tax position is different, so speak to an accountant before choosing.
Individual landlords are restricted by Section 24 and receive a basic-rate tax credit on finance costs rather than deducting them. From 6 April 2027, that credit is set at the new 22% property basic rate. Companies deduct interest as a business expense before corporation tax.
This means repayment mortgages reduce your cash flow without reducing your tax bill. Every investor's tax position is different, so speak to an accountant before choosing.
Interest-only needs an exit plan
The biggest risk with interest-only is reaching the end of the term with no plan. Lenders want to know how you intend to repay, and so should you. Common repayment strategies include:
Write your plan down now, and review it every few years.
- Selling the property at the end of the term
- Selling one or more properties in a portfolio to clear the others
- Refinancing onto a new mortgage, subject to criteria and your age at the time
- Savings or investments built up over the term
Write your plan down now, and review it every few years.
A blended approach
You don't have to choose one or the other for your whole portfolio. Many investors run a mix:
Some lenders also allow overpayments on interest-only loans, usually up to a set percentage each year without penalty. That lets you pay down debt when cash flow is strong, without committing to higher payments when it isn't. [VERIFY overpayment allowances by product]
- Interest-only on newer or growth properties to maximise cash flow while building
- Repayment on older properties or those they plan to keep forever
- Part and part on a single loan, where some lenders allow a split between interest-only and repayment [VERIFY which lenders offer part and part on buy-to-let]
Some lenders also allow overpayments on interest-only loans, usually up to a set percentage each year without penalty. That lets you pay down debt when cash flow is strong, without committing to higher payments when it isn't. [VERIFY overpayment allowances by product]
How to decide
Ask yourself:
Run your deal analysis both ways before you decide. If the property only works on interest-only, that's fine, but know it.
- What's this property for? Cash flow now, or a debt-free asset later?
- Can the rent cover repayment comfortably, with a buffer for voids and repairs?
- What's my exit if I go interest-only?
- Where am I in my investing journey? Early-stage growth usually favours interest-only. Later-stage consolidation often favours repayment.
Run your deal analysis both ways before you decide. If the property only works on interest-only, that's fine, but know it.
How we can help
James Property Mortgages is an introducer, not a lender, and we aren't FCA-regulated ourselves. We introduce investors to regulated brokers who can compare interest-only, repayment and part and part options across the buy-to-let market for your specific plan.
Weighing up your options? Request a free broker introduction at jamesproperty.io/mortgages.
29.09.2026