Offset mortgages explained

An offset mortgage is a home loan where your savings, and with some lenders your current account balance too, are linked to the mortgage so that you pay interest only on the difference between what you owe and what you have¹. If you have a mortgage balance of £100,000 and £15,000 in linked accounts, interest is calculated on £85,000³. The savings are not paid into the mortgage: they stay in your name, earn no interest, and can usually be withdrawn when you need them¹.

The trade-off is that offset deals tend to charge higher rates than standard mortgages, and not many lenders offer them, so your choice can be limited¹. Whether an offset works out better than a cheaper conventional deal depends on how much you have in savings and how the numbers stack up against the alternatives⁴. For a higher-rate taxpayer with a large cash balance, the tax treatment can tip the balance, because offset savings earn no interest and so attract no tax¹.

How an offset mortgage works: you pay interest on the difference

A conventional repayment mortgage charges interest on the whole balance you owe. An offset changes only one thing: the balance the interest is worked out on. Accord Mortgages, Yorkshire Building Society and Coventry Building Society all describe the arrangement the same way, that you are charged interest on the difference between the amount in your savings and the amount borrowed on your mortgage⁸. Barclays puts it in similar terms, that offsetting uses what is in your savings and current account to reduce the mortgage balance you are charged interest on¹¹.

The mechanics are simple in outline. Your mortgage and your linked accounts sit with the same lender, because the two balances have to be netted off against each other⁵. Each day, the lender looks at what you owe and what you hold in the linked accounts, and charges interest on the gap. Coventry Building Society, for example, calculates interest daily, adds it to the mortgage account on the 1st of each month, and works out the offset benefit on the close of business on the last day of each month, applying it on the 1st of the following month¹⁰. first direct gives a worked illustration: a £100,000 mortgage with £20,000 of savings and £1,000 in a current account, all linked, means interest is charged on £79,000¹².

Two points about the arrangement catch people out. First, the savings are not paying the mortgage down. Capital repayments are still based on the full loan amount; the offset arrangement reduces the amount of interest you pay, not the debt itself¹. Second, the savings earn nothing. Accord's terms are blunt about it: no interest will be paid on the money in your savings account¹³. You are, in effect, swapping the interest you could have earned for a guaranteed reduction in mortgage interest, which is why the arrangement tends to suit borrowers with larger cash balances⁴.

There is a family version of the idea. A parent can put savings in an offset account linked to their child's mortgage, which reduces the child's interest payments and can help with affordability checks, without the parent giving the money away¹. The mortgage and the savings must still be with the same provider⁵.

One thing offsetting does not change is your loan-to-value ratio. Because the savings are not paid into the loan, the amount borrowed and the property value are untouched, so the rate bands and deals you qualify for are unaffected by the offset itself⁵. How loan-to-value works generally is covered in loan to value explained.

Your savings stay accessible, but withdrawals cost you the offset

The defining feature of an offset, compared with paying a lump sum into the mortgage, is that the money stays yours. You can access the cash when you need it, although some lenders may require you to keep a minimum balance¹. That makes an offset very different from an overpayment, where the money has gone into the loan and getting it back out means borrowing again.

The cost of a withdrawal is that the offset shrinks pound for pound. Which? gives the example of someone who still owes £250,000 on a mortgage linked to an account containing £20,000: they pay interest on £230,000, but if they withdraw £10,000, interest is charged on £240,000¹. The savings stop working the moment they leave the linked account, and the mortgage interest goes back up from that day.

In practice this makes an offset a home for money you may need: an emergency fund, self-assessment tax set aside by the self-employed, or a short-term savings goal. The trade-off is that money sitting in the linked account earns nothing at all¹³, so every pound in it is a pound not earning interest elsewhere. Whether that is better than keeping the cash in a savings account and taking a cheaper mortgage is the comparison that decides the whole question, and it is covered in overpaying the loan or saving the money instead.

Lower payments or a shorter term: the two ways the saving is used

When the offset reduces the interest you pay, the lender has to decide what happens to the money you have saved. Broadly there are two arrangements, and with most lenders you choose between them, sometimes at application stage.

The first keeps the term and lowers the payments. Barclays states that the interest saving from an offset can be used either to reduce monthly payments over the agreed term or to shorten the mortgage term¹¹. Bank of Scotland describes the lower payments option in more detail: monthly payments adjust automatically based on your offset balance, meaning they are likely to be lower, while the mortgage term and balance are unchanged by offsetting¹⁴. Accord's equivalent, the net payment option, uses the Offset savings to lower monthly mortgage payments now, but the mortgage will not be paid off any sooner¹⁵. Accord's gross payment option works similarly, recalculating the payment every year based on the reduced mortgage balance and the remaining term¹⁵.

The second keeps the payments and shortens the term. Bank of Scotland describes this as monthly payments not changing as often as a result of offsetting, so you are effectively overpaying each month, with the term reduced where possible on a capital and interest mortgage¹⁴. Scottish Widows offers the same choice in its own terms: two options, Reduced Term or Reduced Monthly Payment¹⁶. On its Reduced Term example, offsetting cuts the term of the mortgage by 3 years and 5 months and saves £46,440 in interest payments¹⁶.

Bank of Scotland also offers a third variant: using the offset to reduce the overall mortgage balance without changing the term¹⁴. Scottish Widows adds one restriction worth knowing before you apply: you can only offset against one rate or repayment method, and you must choose which one at application stage¹⁶.

Which arrangement suits you depends on circumstance, not on one being better. Lower payments help if cash flow is tight or your savings balance swings around a lot, since the payment follows the offset balance. A shorter term suits someone whose priority is clearing the debt, and it produces the bigger interest saving over the life of the loan, as the worked examples below show. The general mechanics of repayment mortgages are covered in repayment mortgages explained.

Worked examples: what offsetting saves

The size of the saving depends on three things: how much you offset, how long for, and whether you take the saving as lower payments or a faster repayment. Which? has worked the numbers on a £200,000 repayment mortgage over 25 years at 3%, using Family Building Society's offset mortgage calculator and Santander's mortgage overpayment calculator¹.

With £5,000 of savings offset and the saving taken as lower monthly payments, you would save £3,740 in interest over the term. With £20,000 offset on the same basis, the saving is £14,540¹.

Take the same offsets but keep the payments unchanged, so the mortgage is repaid faster, and the numbers grow. £5,000 offset means the mortgage is repaid after 24 years and 7 months, saving £5,440 in interest. £20,000 offset means the mortgage is repaid after 23 years and 3 months, saving £20,150¹.

The comparison with a plain overpayment is instructive. A one-off £5,000 overpayment on the same mortgage, with the payment reduced, saves £2,113 in interest, against £3,740 for offsetting the same amount¹. The offset saves more here because the money stays offset for the whole term rather than being spent once, though the overpayment has the advantage of permanently reducing the debt. Which? also makes the wider point that there is no tax on the "savings" you make by overpaying your mortgage, which is why the tax section below matters to the comparison¹⁷.

Lenders' own illustrations show the same pattern at different scales. Accord's guide works an example on a repayment mortgage with a £100,000 balance over a 25-year term, at 2.50% fixed for the first two years and then 4.49% for the remaining term, with £15,000 of Offset savings⁸. Lloyds uses a £25,000 savings balance in its example⁵. The figures differ because the inputs differ, but the shape is consistent: the more you offset, and the longer it stays in, the more interest you save.

Rates and costs: offset deals tend to be dearer

The main cost of an offset is the rate itself. Experian notes that offset mortgage rates tend to be higher than those on standard mortgages³, and Lloyds says the same, that rates for offset mortgages may be higher than those for other mortgages⁵. The question is whether the interest you save by offsetting outweighs the extra you pay on the rate, and that depends almost entirely on how much cash you have to link⁴.

Fees are the other part of the cost. Arrangement fees on mortgage deals generally have been substantial in recent years: Which? reported in January 2026 that for those remortgaging, the most common fee on the lowest-rate deals was £1,999¹⁸, and its guidance on fixed-rate deals notes that remortgagers are typically charged higher fees for the deals with the lowest rates, with many close to £2,000¹⁹. An offset deal carries the same sort of upfront fee as any other mortgage, so it belongs in the comparison. The general picture is covered in mortgage fees and charges.

Offset mortgages will often allow you to make overpayments as well, though early repayment charges may apply¹. If your offset deal has a fixed or discounted period, leaving it early, overpaying beyond any allowance, or paying the mortgage off can trigger a charge, exactly as on a conventional deal; Which?'s guides to fixed rate and discounted rate mortgages describe how these periods work¹⁹, and early repayment charges explains how the charges are shown and how to check what yours would be.

Because choice is limited, the range of offset deals on the market is narrower than for standard mortgages, so the comparison is between the few lenders that offer one at all¹. A mortgage broker can see the whole offset market in one place, including broker-only lenders, which matters more than usual in a thin market.

Tax: no interest means no tax on savings

The tax treatment is where an offset can gain an edge that the headline rate does not show. Because the linked savings earn no interest, there is no savings income to tax. Which? puts it directly: you will not pay any tax on savings income, or use up your Personal Savings Allowance, because you will not be earning interest on the money¹. Lloyds makes the same point in four words: with no interest on your savings, there is no tax due⁵. Scottish Widows states that because it does not actually pay interest on offset savings balances, there is no tax liability¹⁶.

This matters most to higher-rate and additional-rate taxpayers¹. A taxpayer in one of those bands pays tax on savings interest above their allowance, so the interest a conventional savings account pays them is worth less than its headline rate. An offset gives a return equal to the mortgage rate, with no tax taken off it, because the return is a reduction in interest charged rather than interest received. Bank of Scotland summarises the position for its own offset: your savings reduce the balance you pay interest on, you earn no interest on the savings, and there is no tax to pay on them¹⁴.

The same logic underlies the comparison with overpaying. Which? notes that there is no tax on the "savings" you make by overpaying your mortgage¹⁷, so both routes deliver a tax-free return; the difference is access, since offset savings can be withdrawn and an overpayment cannot.

One tax point sits on the other side of the ledger for landlords. Landlords can receive a tax credit of 20% of their buy-to-let mortgage interest payments²¹. That relief reduces the effective cost of mortgage interest on a rental property, which changes the sums when comparing an offset against a cheaper standard buy-to-let rate, and it is why the buy-to-let section below is more cautious.

Interest-only offset mortgages

Some lenders do offer interest-only offset mortgages, where monthly payments cover only the interest and the full balance is payable at the end of the term⁵. On the face of it the combination is attractive: the offset reduces the interest charged, and the payments are already interest-only, so the offset directly lowers what you pay each month.

But the combination has a catch that follows from how offsetting works. Because the savings are not paid into the loan, the capital balance does not fall, and on an interest-only mortgage nothing else is reducing it either. Coventry Building Society requires anyone taking an interest-only Offset to have an acceptable repayment plan in place to pay back the amount borrowed at the end of the mortgage term¹⁰. An offset can form part of such thinking, but the linked savings remain withdrawable, so a lender will want to see a credible plan beyond them. Which? has examined how borrowers tackle interest-only mortgages and the repayment strategies lenders expect²².

The rules on interest-only are strict for good reason. The FCA's mortgage rulebook states that a lender may only enter into an interest-only mortgage, or switch a repayment mortgage onto an interest-only basis, if it has evidence that the customer will have in place a clearly understood and credible repayment strategy with the potential to repay the capital borrowed and any interest reasonably expected to accrue²³. The Mortgage Market Review put the same requirement in place at policy level: only allowing a borrower to take out an interest-only mortgage where there is a credible repayment strategy in place²⁴.

first direct lists interest-only Offset Mortgages among its product types, though it notes that offset mortgages are only available to existing Offset Mortgage customers²⁵. How interest-only works generally, and what lenders accept as repayment strategies, is covered in interest-only mortgages explained and repayment vs interest-only.

Offset on buy-to-let: available, but less common

Most offset products are designed for residential owner-occupied mortgages. Some lenders offer them for buy-to-let purposes, though availability is more limited⁶. So an offset on a rental property is possible, but the market is thinner and the choice of deals smaller than for a home you live in.

The tax position is the main reason to think carefully before choosing one. A residential borrower gets a tax-free return from offsetting because the alternative, savings interest, would be taxed. A landlord's position is different: mortgage interest on a rental property attracts relief as a tax credit of 20% of the interest payments²¹, so the effective cost of buy-to-let mortgage interest is already reduced. An offset deal carrying a higher rate than a standard buy-to-let mortgage may cost more even after the offset saving, once that credit is taken into account. The comparison has to be done on the actual numbers for the property and the savings involved.

The wider point is that an offset is one of several additional features lenders may offer on a mortgage, alongside flexible or cashback arrangements²⁶. On a buy-to-let, where the borrowing is a business cost, a landlord weighing an offset compares the rate premium against the offset saving and the tax credit, rather than the personal savings tax position a residential borrower faces. How the lending itself works is covered in buy-to-let mortgages explained.

Protection: where FSCS cover for offset savings is unclear

This is the one area where the sources genuinely disagree, and it is worth asking a lender directly before committing savings to an offset.

On one side, the Nottingham Building Society's guidance states that offset savings are usually not covered by the Financial Services Compensation Scheme (FSCS) in the same way as a standard savings account⁶. On the other, Yorkshire Building Society states plainly that deposits in the savings element of its Offset mortgage are covered by the FSCS⁷, and its offset options guide repeats the point⁹. Both cannot be true of the same arrangement, and the difference may come down to how each lender holds the linked money, which is exactly why the question needs answering for the specific product in front of you.

The FSCS position on the mortgage side is clearer. FSCS protects mortgage advice²⁸, but its own leaflet draws a line: whilst we cover the advice, we do not cover the lending or administration costs on the mortgage itself²⁹. So if you were badly advised to take an offset that did not suit you, the FSCS may be able to help; if the mortgage simply turns out to be expensive, that is not what the scheme covers.

There is also a practical argument that the exposure is smaller than it looks. Because offset savings earn no interest¹³, the loss if a lender failed would be the capital itself, and the offset arrangement means that money is working against a debt owed to the same institution. But that is a description of the structure, not a substitute for knowing whether the deposit is protected. Your rights on a mortgage generally are set out in mortgage rules, your rights and protection.

Who offers offset mortgages

Not many lenders offer offset mortgages, so your choice can be limited¹. The lenders that do are a mix of high street banks, building societies and broker-only brands.

• Barclays offers an offset mortgage that it says can lower monthly payments or reduce the mortgage term, using savings and current account balances¹¹.
• Lloyds Bank offers an offset mortgage and notes that the mortgage and savings account must be with the same provider⁵.
• first direct offers Offset Mortgages, including an interest-only version, though only to existing Offset Mortgage customers²⁵.
• Bank of Scotland and Scottish Widows Bank both run offset facilities for existing customers, with the choice of a shorter term or lower payments¹⁴.
• Coventry Building Society links Offset savings to its mortgage and charges interest only on the difference between the mortgage amount and the savings¹⁰.
• Yorkshire Building Society offers Offset mortgages, including its Offset Plus arrangement for savers and borrowers, and states that deposits in the savings element are FSCS covered⁷.
• Accord Mortgages, Yorkshire Building Society's broker-only lending brand, offers offset mortgages linking the loan with one or more savings accounts¹⁵.
• The Nottingham offers offset mortgages alongside its repayment range⁶.
• Leeds Building Society explains offset arrangements in its savings guidance, treating the offset as one way to use savings against borrowing³⁰.

If you are weighing an offset against the alternatives, the pages on overpaying your mortgage, fixed rate mortgages and tracker mortgages set out how each of those deals behaves, and mortgages: a complete guide pulls the whole subject together.