Is it better to overpay my mortgage or put the money in savings?

For most people paying tax on their savings interest, overpaying wins. Overpaying returns your mortgage rate, tax-free and guaranteed, because every pound you knock off the balance is a pound that stops accruing interest. Savings interest is taxable once it goes beyond your Personal Savings Allowance of £1,000 for a basic-rate taxpayer or £500 for a higher-rate taxpayer, and nil for additional-rate taxpayers (HMRC). To match a 4.32% mortgage rate, a higher-rate taxpayer needs a savings account paying 7.2% gross, and a basic-rate taxpayer needs 5.4%. The best one-year fixed savings bond available on 6 August 2026 paid 4.91% (Habib Bank Zurich UK, via MoneySavingExpert), so neither figure exists in the market. The exception is money held tax-free in a cash ISA, where the comparison is rate against rate, and the best one-year fixed cash ISA at 4.72% (Al Rayan Bank, Moneyfacts, 4 August 2026) does beat a 4.32% mortgage by a small margin.

How much can I overpay my mortgage without a penalty?

Most UK lenders let you overpay 10% of your balance each year while you're inside a fixed, tracker or discounted deal, without triggering an early repayment charge. On a £220,000 mortgage that's £22,000 a year, or roughly £1,833 a month, which is far more headroom than most people will ever use. The detail varies: some lenders calculate the 10% on the balance outstanding at the start of the calendar year, others on the original loan amount, and the reset date can be the anniversary of the account or of your current deal. Go beyond the allowance and the early repayment charge is typically 1% to 5% of the excess, usually falling in each year of the fixed term. Once your deal ends and you're on the standard variable rate, you can normally overpay without limit. Check your lender's specific rules in writing before making a large one-off payment.

Does overpaying my mortgage reduce my monthly payment or the term?

By default most lenders keep your monthly payment the same and shorten the term, which is the option that saves the most interest. On a £220,000 mortgage at 4.32% over 25 years, a single £10,000 overpayment cuts roughly 23 months off the term and saves about £18,200 in interest if the rate held for the full remaining term. Some lenders will instead recalculate and lower your monthly payment, which frees up cash flow now but saves far less interest overall. You usually have to ask for that explicitly. If your priority is a lower monthly bill rather than a shorter loan, ask your lender which option applies before you overpay, because switching it afterwards is not always straightforward.

Should I overpay before remortgaging or keep the cash?

If overpaying moves you into a lower loan-to-value band before your fix expires, do it. Lenders price in bands at roughly 60%, 75%, 80%, 85%, 90% and 95% LTV, and crossing a threshold can change the rate you're offered on the whole loan, not just on the amount you paid off. On 5 August 2026 the cheapest two-year fix at 60% LTV was 4.32% against 4.78% at 90% LTV, a gap of 0.46 percentage points worth roughly £55 a month on a £210,000 mortgage (Moneyfacts). If you're nowhere near a band edge, keeping the cash and using it to reduce the new loan at completion achieves almost the same result while leaving the money accessible in the meantime. Check your property's likely valuation and your outstanding balance first, then work out how far you are from the next band down.

Overpay or save? You'd need a 7.2% savings account

There's a few hundred pounds sitting in your current account at the end of each month that you haven't decided what to do with, and it's been there long enough to start nagging at you. Overpay the mortgage and it's gone for good, locked into bricks you can't get at if the boiler dies. Leave it in savings and you're pretty sure inflation is quietly eating it. Your fix ends next year, Bank Rate hasn't moved since 18 June 2026, and nobody will give you a straight answer about which one is actually better.

Here's the straight answer, and it's more lopsided than most people expect. To beat overpaying even the cheapest mortgage on the market today, a higher-rate taxpayer would need a savings account paying 7.2% gross. Nothing in Britain pays that. The best one-year fixed bond on 6 August 2026 paid 4.91% (Habib Bank Zurich UK, via MoneySavingExpert).

The only rate that matters is the one you're actually paying

Overpaying a mortgage isn't an investment and it doesn't produce a return you can spend. What it does is stop a cost. Every pound you knock off the balance is a pound that stops accruing interest at your mortgage rate, for as long as the loan would otherwise have run. That makes the "return" exactly equal to your mortgage rate, it's guaranteed, and it's completely untaxed, because there's no income to tax.

So the number you need isn't the best-buy rate in the papers. It's the rate on your own mortgage statement. On 5 August 2026 the cheapest two-year fix in the market was 4.32% at 60% loan-to-value (Danske Bank, £1,124 fee, Moneyfacts). The whole-market average two-year fix was 5.62% and the average five-year fix 5.66% as at 29 July 2026, with the average standard variable rate at 7.13% (Moneyfacts). That's a spread of nearly three percentage points between the luckiest borrower and the one who let their deal lapse, and it changes the answer completely.

So before you compare anything, go and find the rate on your latest mortgage statement. If you've slipped onto a standard variable rate near 7.13%, the rest of this article is academic: overpaying wins by a distance no savings account can touch.

What you'd have to earn to beat it

Savings interest is taxed as income once it goes past your Personal Savings Allowance, which is £1,000 a year for a basic-rate taxpayer, £500 for a higher-rate taxpayer and nothing at all for additional-rate taxpayers (HMRC, 2026/27 tax year). Overpaying isn't taxed at all. So to compare them fairly you have to gross up the savings rate.

The sum is simple: divide your mortgage rate by one minus your tax rate. Here's what that produces at today's rates.

The gross savings rate you'd need to match overpaying:

Mortgage at 4.32% (best-buy 2-year fix): 4.32% tax-free, 5.40% for a basic-rate taxpayer, 7.20% for a higher-rate taxpayer · Mortgage at 5.62% (average 2-year fix): 5.62% tax-free, 7.02% basic rate, 9.37% higher rate · Mortgage at 7.13% (average SVR): 7.13% tax-free, 8.91% basic rate, 11.88% higher rate.

Best rates actually available on 6 August 2026: one-year fixed bond 4.91% (Habib Bank Zurich UK), flat-rate easy access 4.52% (cahoot Simple Saver Issue 18), one-year fixed cash ISA 4.72% (Al Rayan Bank), easy access cash ISA 4.51% (Trading 212). Sources: MoneySavingExpert and Moneyfacts, 4 to 6 August 2026.

Line those two lists up and the gap is stark. Every single taxed cell in the first list is higher than the best rate available in the second. Once your savings interest is being taxed, there is currently no UK savings account that beats overpaying even the very cheapest mortgage on the market, let alone an average one.

So if your savings are already outside an ISA and you're paying tax on the interest, the comparison isn't close and you can stop running it. That money is worth more against the mortgage.

£10,000, two ways

Take a £220,000 repayment mortgage over 25 years at 4.32%, which costs about £1,200 a month. You've got £10,000 spare.

Pay it off the mortgage and the balance drops to £210,000. Keep the monthly payment the same and the term shortens by roughly 23 months, saving about £18,200 in interest across the life of the loan (calculated using the standard UK repayment mortgage formula, assuming the rate held for the full remaining term, which it won't). In the first year alone, it stops £432 of interest you'd otherwise have paid.

Put the same £10,000 into the best one-year fixed bond at 4.91% and it earns £491 gross. A higher-rate taxpayer who's already used their £500 allowance keeps £294.60. A basic-rate taxpayer in the same position keeps £392.80. Both lose to the £432 of interest the overpayment stops.

There is one case where saving wins, and it's worth being honest about it. A basic-rate taxpayer with no other savings income has the full £1,000 allowance free, so the whole £491 is tax-free and beats the £432 by £59. That's a real advantage, and it comes with the money still being accessible. It's also small, and it disappears the moment you have any meaningful savings elsewhere.

So if you're a higher-rate taxpayer, that £10,000 is worth £137 more a year against the mortgage than in the best bond in the country. If you're a basic-rate taxpayer with an empty Personal Savings Allowance, saving edges it by £59 and buys you liquidity, which is a reasonable price for keeping your options open.

The allowance breaks at £10,183

That basic-rate advantage has a hard ceiling, and it arrives sooner than people think. At 4.91%, a higher-rate taxpayer uses up the entire £500 Personal Savings Allowance with just £10,183 of savings. A basic-rate taxpayer burns through the £1,000 allowance at £20,367. Every pound above those thresholds earns interest that's taxed at 40% or 20%, which drops the effective return to 2.95% or 3.93% respectively.

Cash ISAs are the way round it, and this is the one place saving genuinely competes. Inside an ISA there's no tax, so it's rate against rate. The best one-year fixed cash ISA on 4 August 2026 paid 4.72% (Al Rayan Bank, Moneyfacts), which beats a 4.32% mortgage by 0.40 percentage points. On £10,000 over five years, that's £12,594 in the ISA against £12,355 of mortgage interest avoided, a difference of about £239.

That advantage is shrinking. The Autumn Budget 2025 announced that from 6 April 2027 the annual cash ISA subscription limit falls from £20,000 to £12,000 for anyone under 65, with the overall £20,000 ISA allowance unchanged and over-65s keeping the full cash limit. HMRC's technical consultation on the draft regulations closed on 2 August 2026 and the rules aren't law yet, so treat the detail as announced rather than settled. For the current 2026/27 tax year, the full £20,000 cash ISA allowance is still available to everyone.

So if you're going to hold cash rather than overpay, get it inside a cash ISA this tax year while the £20,000 allowance is still open to you. From April 2027 the tax-free shelter is likely to be considerably smaller, and everything outside it goes back to losing the comparison.

The return that neither calculation captures

There's a third effect that doesn't show up in either interest sum, and for anyone with a fix expiring it can dwarf both. Lenders price mortgages in loan-to-value bands, roughly at 60%, 75%, 80%, 85%, 90% and 95%. Cross a threshold and the rate changes on the entire loan, not just on the slice you paid off.

Say your home is worth £280,000 and you owe £220,000. That's 78.6% LTV, which puts you in the 80% band. A £10,000 overpayment takes the balance to £210,000, exactly 75%, and moves you down a band before you apply for a new deal. The size of that prize depends on the lender, but the direction of travel is clear from the market's extremes: on 5 August 2026 the cheapest two-year fix at 60% LTV was 4.32% against 4.78% at 90% LTV, a 0.46 percentage point gap worth about £55 a month on a £210,000 mortgage (Moneyfacts). Individual band steps are smaller than that, but they're not nothing, and they apply to every pound you owe for the whole of your next fix.

Timing matters here. Your lender will use a valuation, so overpaying £900 when you're 0.3% away from a band edge is worth far more than overpaying £9,000 when you're stranded in the middle of one. Our remortgage preparation guide covers how to work out where you actually sit before you apply.

So if your fix ends within the next 12 months, work out your current LTV first. Overpaying just enough to cross into the next band down is the single highest-return use of spare cash available to you right now.

When keeping the cash is still the right call

None of this holds if the money is your safety net. An overpayment is close to irreversible: most lenders won't let you draw it back, and a further advance or remortgage to release it later comes with fees, a fresh affordability check and a rate you can't predict. Three to six months of essential outgoings should sit in an accessible account before a single pound goes toward the mortgage. That's not a maths question, it's an insurance one.

Two other constraints are worth checking. Most lenders cap penalty-free overpayments at 10% of your balance each year while you're inside a fixed deal, which on £220,000 is £22,000 a year, more than most people will use, but the calculation basis and reset date vary by lender. Go over and the early repayment charge is typically 1% to 5% of the excess. And if you're carrying credit card or personal loan debt at 8% or more, neither overpaying nor saving is the right answer: that debt is costing you roughly double either option.

Britain is already voting with its wallet on this. Santander customers overpaid their mortgages by more than £894 million in the first four months of 2026 alone (Santander UK, reported 12 May 2026), at a time when the average easy access savings account paid just 2.53% (Moneyfacts UK Savings Trends Treasury Report, published 16 July 2026). Against that 2.53%, which is what most people are actually earning rather than the best-buy 4.91%, the overpayment case is overwhelming for anyone at any tax rate.

So the order is fixed: emergency fund first, expensive unsecured debt second, mortgage overpayment third, taxable savings last. If you're not through the first two, today's rates don't change your priorities.

What this means for you

Frankly, if you're a higher-rate taxpayer with an emergency fund in place and no expensive debt, the maths points one way and there's very little to argue about: overpay. You'd need a 7.2% savings account to match a 4.32% mortgage and a 9.37% account to match the market average of 5.62%, and neither exists. If you're a basic-rate taxpayer with your full £1,000 allowance unused and less than about £20,000 saved, you can reasonably keep the cash in a top-paying account or a cash ISA and lose very little either way, so choose on liquidity rather than on yield.

Whichever camp you're in, do the loan-to-value check before your fix expires, because that's where the real money is hiding. Run your own numbers through our mortgage overpayment calculator first, then read our piece on locking in a rate now versus waiting, since the two decisions interact. Bank Rate is on hold at 3.75% with three of nine MPC members having voted for a rise on 30 July 2026 and the next decision due on 17 September 2026 (Bank of England), so betting on cheaper money arriving soon is a thin plan to build around. Most people who actually sit down and run these figures end up putting the money against the mortgage and sleeping better for it.