Most buy-to-let mortgages are interest-only, which keeps monthly payments low but means you do not chip away at the loan. Understanding how this works is essential for landlords. This guide explains interest-only buy-to-let mortgages: how they work, why they are common, their pros and cons, and the all-important repayment strategy.
What interest-only means
With an interest-only mortgage, your monthly payments cover only the interest, not the capital, so the amount you owe stays the same throughout the term. At the end, you must repay the full loan in one go. This differs from a repayment mortgage, where each payment includes some capital, gradually clearing the loan. Interest-only keeps payments lower but leaves the original debt outstanding until the end.
Why it is common in buy-to-let
Interest-only is common in buy-to-let because it maximises monthly cash flow: lower payments mean more of the rent is left as profit each month, as our guide to buy-to-let mortgages explained explains. Landlords often value this income and plan to repay the capital by selling the property later. This focus on income and eventual sale suits the investment nature of buy-to-let, which is why interest-only dominates the market.
The advantages
The main advantage is higher monthly cash flow, since you pay only the interest, leaving more rental profit. This can make a rental more financially viable, help meet the rental cover test, and free up income for other investments or a buffer. For landlords focused on income and using property as a long-term asset expected to grow in value, interest-only can be an efficient way to structure the borrowing.
The drawbacks
The key drawback is that you do not build equity through your payments, and you still owe the full loan at the end of the term, which you must repay. You are therefore more reliant on the property's value, since selling is the usual repayment route, and a fall in value could leave a shortfall. Interest-only also means paying interest on the full balance throughout, with no reducing capital.
The repayment strategy
Because the full loan must be repaid at the end, you need a clear repayment strategy. For most buy-to-let landlords, this is selling the property, using the sale proceeds to clear the mortgage and keep any remaining equity. Others plan to repay from savings or by refinancing. Having a realistic plan to repay the capital is essential, since the debt does not reduce on its own over the term.
Relying on the property's value
If your strategy is to sell to repay, you are relying on the property being worth enough to clear the mortgage and ideally leave a profit. Usually this is comfortable, since buy-to-let loans are often a moderate proportion of the value, but a significant fall in prices could erode the cushion. Being aware of this reliance on value, and not over-borrowing, helps ensure your exit strategy remains sound.
Interest-only versus repayment buy-to-let
While interest-only dominates buy-to-let, some landlords choose repayment, gradually clearing the loan so they own the property outright over time, trading lower monthly profit for a reducing debt and growing equity. This can suit those prioritising long-term security over maximum income. Choosing between interest-only and repayment depends on your goals: cash flow and flexibility, or steadily owning the asset, which is a personal investment decision.
An example of interest-only
Suppose you have a £150,000 interest-only buy-to-let at 5%. Your monthly payment covers only the £625 of interest, with nothing off the £150,000 balance, which remains owed throughout. On a repayment basis, your payment would be higher but would gradually clear the loan. The interest-only structure keeps the monthly cost down and the rental profit up, at the cost of still owing the full £150,000 at the end.
Why lenders accept sale as a strategy
Lenders accept selling the property as a repayment strategy for interest-only buy-to-let because the loan is usually a moderate proportion of the value, so a sale should comfortably clear it. This differs from interest-only on a residential mortgage, where lenders scrutinise the repayment plan more closely. The investment nature of buy-to-let, and the equity cushion from the deposit, make sale a generally accepted way to repay the capital.
Part interest-only, part repayment
Some landlords choose a part interest-only, part repayment structure, paying off some capital while keeping payments lower than full repayment. This gradually reduces the debt and builds equity, while preserving more cash flow than a full repayment mortgage. It is a middle path between maximising income and steadily owning the property, which can suit landlords who want some debt reduction without sacrificing all their monthly profit.
Overpaying an interest-only buy-to-let
Even on an interest-only deal, you can often overpay within your lender's annual allowance, reducing the balance and the interest you pay, as our guide to overpaying explains. This lets income-focused landlords still chip away at the debt when they have spare funds. Overpaying an interest-only buy-to-let combines the cash-flow benefit of low required payments with the option to reduce the loan when it suits you.
Review your strategy regularly
Because the capital must eventually be repaid, it is wise to review your repayment strategy regularly, checking the property's value still comfortably covers the loan and your plans remain realistic. Market changes can affect your cushion. Revisiting your interest-only strategy from time to time, rather than ignoring it until the term ends, ensures you remain on track to repay the loan and are not caught out by changing circumstances.
Cash flow versus ownership
The core choice with interest-only is between cash flow and ownership. Interest-only maximises monthly income but leaves the debt in place, while repayment sacrifices some income to steadily own the property. Neither is simply better; it depends on whether you prioritise income now or building equity and owning outright later. Being clear about which goal matters more to you guides the choice between interest-only and repayment for each property.
Plan for the end of the term
Because an interest-only loan must be repaid in full at the end, it is important to plan for that point well in advance, whether through sale, refinancing, or savings, as our guide to remortgaging a buy-to-let explains. Most landlords simply remortgage onto a new interest-only deal or sell. Having a clear, realistic plan for the end of the term, and reviewing it over time, ensures the interest-only structure never catches you out.
Whichever route you choose, the golden rule with interest-only is never to lose sight of the fact that the full loan still has to be repaid one day, so keep your repayment strategy realistic and under regular review and the structure will serve you well.
In short
Interest-only buy-to-let mortgages mean you pay only the interest, keeping payments low and cash flow high, but the full loan remains and must be repaid at the end of the term, usually by selling. They maximise rental profit but build no equity through payments and rely on the property's value for repayment. A clear repayment strategy is essential. Some landlords prefer repayment for steadily owning the property.
Where to get help and next steps
Read our guides to buy-to-let mortgages, remortgaging a buy-to-let, and is buy-to-let worth it. This is general information, not mortgage, tax or financial advice.