Buy-to-Let
Offset Buy-to-Let Mortgages
An offset buy-to-let mortgage links savings to the mortgage, so you pay interest only on the difference. It suits landlords who hold cash for repairs, voids or tax bills. Few lenders offer it and rates are usually higher, so it only pays if you keep enough cash in the account.
Written and reviewed by Davi Thakar, CeMAP qualified mortgage and protection adviser Updated
An offset buy-to-let mortgage links a savings account to your mortgage, so you only pay interest on the balance minus your savings. It can save money for landlords who keep a large cash reserve, but rates are usually higher and few lenders offer it.
If you owe £150,000 and keep £20,000 in the offset account, you pay interest on £130,000. Your savings earn no interest, but they stay accessible for repairs, voids or a tax bill.
This guide covers how offset works for landlords, when it beats a standard deal or overpaying, and the drawbacks. For the wider picture, see our complete buy-to-let mortgage guide.
Is an offset buy-to-let mortgage worth it?
Only if you keep enough cash in the account, most of the time. The interest you save has to outweigh the higher rate and any bigger fee. Landlords who hold a healthy reserve and pay higher-rate tax on savings interest gain the most. If your balance is usually small, a standard deal is normally cheaper.
Why do landlords use offset?
- Cash reserves. Most landlords keep money aside for repairs, void periods and tax. In an offset account it reduces mortgage interest instead of sitting idle.
- Tax. Savings interest is taxable. Interest you avoid paying on the mortgage is not taxed as income, so for higher-rate taxpayers the saving can beat a savings account.
- Flexibility. Unlike an overpayment, the money is still there if you need it.
- Saving for the next deposit. Cash building up for your next purchase works against the mortgage while you wait.
Illustration only
A landlord with a £160,000 interest-only mortgage keeps £25,000 in reserve on average. An offset deal at 5.8% charges interest on £135,000, about £7,830 a year. An ordinary deal at 5.4% charges £8,640, but the £25,000 could earn 4% in savings, £600 after 40% tax, bringing the net cost to £8,040. The offset comes out around £210 a year ahead. For an individual landlord, the 20% interest credit on both deals narrows that to about £50. With a smaller reserve, or a bigger rate gap, the ordinary deal wins.
The maths depends on how much cash you really keep in the account. Look at your bank statements for the last year, not the figure you hope to hold.
Real client case: keeping £75,000 of savings working
Our client, an existing landlord, was buying another investment property for £350,000 with a 30% deposit, a mortgage of around £245,000. They also had £75,000 in savings. They could have put more of it into the purchase, but wanted it kept available for maintenance, unexpected costs and their next investment. Their priority was keeping the monthly interest down.
We reviewed their existing properties, rental income, savings and plans, and rather than choosing on headline rate alone we looked at offset. We found a specialist offset buy-to-let mortgage that linked their savings to the mortgage, so with the full £75,000 in the account interest is charged on around £170,000 rather than £245,000, and the money is still theirs to use. The mortgage completed.
What this shows: if you hold large cash reserves anyway, an offset can cut your interest without locking the money away. Compare it on what you will really keep in the account.
How does tax relief interact with offset?
Individual landlords cannot deduct mortgage interest from rent. They get a basic-rate credit instead, as GOV.UK explains in its guide to finance cost relief for residential landlords. Paying less interest therefore also means a smaller credit. The credit is 20% now and 22% from April 2027.
Companies can deduct interest on property loans as a cost, as set out on GOV.UK’s page on paying tax on rental income. For a company, offset reduces both the interest and the deduction, so the saving is smaller in after-tax terms. Your accountant can run the figures for your structure.
What are the drawbacks?
- Fewer lenders offer offset buy-to-let, especially for limited companies.
- Rates and fees are usually higher than the cheapest standard products.
- Your savings earn no interest of their own.
- Interest relief. For individual landlords, reducing interest by offsetting also reduces the basic-rate credit.
- Discipline. The saving disappears if the reserve gets spent on other things.
Should you offset or overpay?
| Offset | Overpaying | |
|---|---|---|
| Access to the money | Yes | Usually no |
| Interest saving | While the cash stays | Permanent |
| Rate | Usually higher | Standard rates |
| Limits | None beyond the balance | Often an annual allowance before charges |
| Best for | Landlords holding large reserves | Landlords with spare cash they will not need |
If you overpay, check the early repayment charge allowance on your deal first. Our guides to interest-only buy-to-let and repayment buy-to-let explain how each repayment method affects your balance over time.
Which situations do lenders see most?
These are illustrative situations, not Option Finance client outcomes.
Large repair fund
You hold a big reserve for roofs, boilers and voids across several properties. Offset puts that cash to work without locking it away.
Works when the reserve stays highSaving up for the tax bill
You set aside money through the year for Self Assessment. It reduces interest until January and July.
Useful, but the balance drops twice a yearSmall reserve, tight budget
You keep a few thousand pounds at most. The higher rate usually costs more than the offset saves.
A standard deal often winsLimited company landlord
You buy through an SPV and want offset. Very few lenders offer it to companies.
Expect a short list of optionsWhat does the lender check?
An offset buy-to-let is assessed like any other buy-to-let. The lender looks at the rent against the payment at its stress rate, your deposit, your credit file and your experience. The savings in the account do not usually count towards the rental test. Some products let you link family members’ savings, which need their own paperwork.
Our broker fee is £499 in total: £299 on application and £200 when a mortgage offer is issued. The £299 is fully refundable if the application is declined. Your initial consultation is free.
Frequently asked questions
Can I get an offset buy-to-let mortgage?
Yes, from a small number of lenders. Rates are usually higher than standard buy-to-let deals.
Is an offset mortgage worth it for a landlord?
It can be if you keep a substantial cash reserve in the account most of the time, especially as a higher-rate taxpayer. Otherwise a standard deal is usually cheaper.
Can I offset other people’s savings?
Some offset products allow family members’ savings to be linked. Check the lender’s rules.
Are offset mortgages available to limited companies?
Very few lenders offer them to companies.
Do I earn interest on money in the offset account?
No. Instead of earning interest, the savings reduce the balance you are charged mortgage interest on.
Does offsetting affect my mortgage interest tax credit?
Yes. Individual landlords get a basic-rate credit on the interest they pay, so paying less interest also means a smaller credit.
Can I take money out of an offset account at any time?
Usually yes. That access is the main advantage over overpaying, but check the lender’s terms.
Speak to Option Finance about offset buy-to-let
We will tell you straight whether offset beats a standard deal or overpaying, using the cash you actually hold rather than a best-case figure.
Book a free initial consultation using the enquiry form below. See our buy-to-let mortgage advice, our buy-to-let remortgage guide and our summary of buy-to-let tax changes for 2026.
Talk through your mortgage options
Tell us about your plans and circumstances. Your initial consultation is free.
Some buy-to-let and commercial mortgages are not regulated by the Financial Conduct Authority. Regulation depends on the mortgage type and circumstances.
Talk through your mortgage options
Tell us about your plans and circumstances. Your initial consultation is free.
Written and reviewed by Davi Thakar
Director & Senior Mortgage Broker
CeMAP Qualified Mortgage and Protection Adviser
Davi founded Option Finance with a vision to deliver transparent mortgage advice from a wide panel of lenders. With over 10 years in financial services, he specialises in complex cases including adverse credit, self-employed borrowers with limited trading history, and large buy-to-let portfolios. He works directly on complex cases and explains each option clearly.
Meet Davi Thakar
