An offset mortgage links your savings to your mortgage so they reduce the interest you pay, while you keep access to the money. It is a clever option for some, but not for everyone. This guide explains offset mortgages: how they work, an example, their pros and cons, and who they suit.
What an offset mortgage is
An offset mortgage links a savings account to your mortgage, so your savings balance is set against, or offsets, your mortgage balance when interest is calculated. You pay interest only on the difference. Crucially, your savings are not used to repay the mortgage; they remain yours to access, but while they sit in the linked account, they reduce the interest charged on your mortgage.
How it works
Suppose you have a £200,000 mortgage and £20,000 in linked savings. With an offset, you pay mortgage interest on only £180,000, the difference, rather than the full £200,000. Your savings do not earn interest themselves, but they save you the higher mortgage interest on that amount, which is usually a better deal. You can still withdraw the savings if you need them, though doing so reduces the benefit.
The advantages
Offsetting reduces the interest you pay, which can shorten your mortgage or lower your payments, while you keep full access to your savings, unlike overpaying, which ties the money up, as our guide to remortgaging versus overpaying explains. It can also be tax-efficient, since you save mortgage interest rather than earning taxable savings interest. For savers with a mortgage, an offset can be an efficient way to use their money.
The disadvantages
The trade-offs are that your linked savings earn no interest of their own, offset mortgage rates can be a little higher than standard deals, and fewer lenders offer them. So the benefit depends on having meaningful savings to offset; with little in savings, the higher rate may outweigh the saving. Weighing the offset benefit against any rate premium is key to deciding whether it is worthwhile.
An example of the benefit
The more savings you hold, the greater the benefit. Someone with substantial savings offsetting a mortgage can save a lot of interest and potentially clear the mortgage years early, while keeping the savings available. Someone with little in savings gains less and may be better off with a cheaper standard deal. So an offset rewards those with a healthy savings balance relative to their mortgage.
Who an offset suits
Offset mortgages suit people with significant savings who want to reduce mortgage interest while keeping access to their money, and higher-rate taxpayers, for whom the tax efficiency is greater. They suit less well those with little in savings or who would be better served by a lower standard rate. As our guide to mortgage basics notes, the right product depends on your circumstances.
Offset versus overpaying
An offset and overpaying both reduce mortgage interest, but differ in access. Overpaying reduces your balance permanently and saves interest, but ties the money up, while offsetting saves interest while keeping your savings accessible, as our guide to how repayment works relates. If you value access to your money, an offset may suit; if you are happy to lock it away, overpaying a cheaper mortgage might save more.
Reducing interest or term
With an offset, you can usually choose how to take the benefit: lower monthly payments, or keeping payments the same and shortening the term, clearing the mortgage years early. Reducing the term often saves the most interest overall, while lower payments help monthly cash flow. Deciding how to use the offset benefit lets you direct it towards whichever goal matters most to you, which is a useful flexibility of these mortgages.
Family offset mortgages
Some lenders offer family offset mortgages, where a family member's savings are linked to the borrower's mortgage to reduce the interest, helping a first-time buyer without the family member giving the money away. The relative keeps their savings but earns no interest on the offset amount. This can be a way for family to help without a gifted deposit, as our guide to gifted deposits explains by comparison.
Current accounts and offsets
Some offset mortgages link not just savings but also a current account, so your everyday balance offsets the mortgage too, maximising the benefit while money sits in your account. This can make an offset more effective for those who keep meaningful balances. Understanding exactly what can be offset, savings, current accounts, or both, helps you judge how much benefit an offset would bring in your circumstances.
The tax angle
Offsets can be tax-efficient because you save mortgage interest rather than earning taxable savings interest. For higher-rate taxpayers, who would pay more tax on savings interest, this benefit is greater, since saving mortgage interest is effectively a tax-free return equal to your mortgage rate. This tax angle is one reason offsets particularly appeal to higher earners with significant savings, as our guide to overpaying relates.
Offset versus a savings account
Whether an offset beats keeping a regular savings account depends on the rates. If your mortgage rate is higher than what your savings would earn after tax, which is often the case, offsetting saves you more than the savings would earn. If savings rates were higher than your mortgage rate after tax, a separate account might win. Comparing the two, including tax, shows whether an offset is the better home for your savings.
Who benefits most
Offsets benefit most those with significant savings relative to their mortgage and, especially, higher-rate taxpayers, for whom the tax efficiency is greatest. A borrower with large savings can save substantial interest and clear the mortgage early, while keeping the money available, as our guide to overpaying compares. With little in savings, the often higher offset rate may outweigh the benefit, so the savings balance is what makes an offset worthwhile.
Weighing the rate premium
Because offset mortgages can come at a slightly higher rate than standard deals, and are offered by fewer lenders, it is important to weigh the offset benefit against any rate premium. If your savings are large enough, the interest saved outweighs the premium; if not, a cheaper standard deal may be better. Doing this comparison, ideally with a broker, shows whether an offset genuinely leaves you better off.
Ultimately, an offset is a specialist tool that rewards savers, particularly higher-rate taxpayers, with meaningful balances, so if that describes you it is well worth comparing against standard deals, and if it does not, a simpler, cheaper mortgage will usually serve you better.
Run the comparison on your own savings, mortgage rate and tax position, and the answer to whether an offset is worth it usually becomes clear quite quickly.
In short
An offset mortgage links your savings to your mortgage so they reduce the interest charged, while you keep access to the money. You pay interest only on the difference between your mortgage and savings. It can reduce interest, shorten the mortgage and be tax-efficient, but your savings earn nothing and rates can be higher. Offsets suit those with significant savings; with little saved, a cheaper standard deal may be better.
Where to get help and next steps
Read our guides to how a mortgage works, remortgaging versus overpaying, and repayment versus interest-only. This is general information, not mortgage or financial advice.