Overpaying isn't one thing, it's six different tactics, each suited to a different situation and budget. Pick the right one for your circumstances and you can clear your mortgage up to a decade early. Pick the wrong one and you'll underperform.
The simplest and most popular. Set a standing order for £100, £200 or £500 extra each month, starting from the first month of your fix. The interest saving compounds from day one.
Best for: anyone with consistent spare monthly income. Pros: easy to set up, easy to stop, maximum compounding. Cons: requires budget discipline; tempting to cut back when life gets expensive.
Wait until you've accumulated savings in a high-interest account, then pay off a chunk in one go each year, usually just before your 10% allowance resets.
Best for: people with variable income (bonuses, self-employed), or savers who prefer visible progress. Pros: maximises interest on the savings you accumulate first; forces annual review. Cons: you're holding cash at savings rates while paying mortgage rates in the meantime, usually the worse option by a small amount.
Round your monthly mortgage payment up to the nearest £50 or £100. If your contractual payment is £1,247.83, you pay £1,300. You barely notice the extra £52, but it shaves years off the term.
Best for: people who struggle to maintain bigger overpayments. Pros: almost invisible in the budget, psychologically easy, self-sustaining. Cons: the overpayment is small.
£1,247.83 payment rounded up to £1,300 adds £52.17/month. Over a 25-year £200k mortgage at 4.5%, that's roughly £10,000 in interest saved and 16 months knocked off the term. From payments you'd barely miss.
When you remortgage, keep your monthly payment the same as your old deal, even though the new (usually lower) rate means the contractual payment has fallen. The difference automatically becomes an overpayment.
Best for: anyone who's already adjusted their budget to the old payment and doesn't need the relief. Pros: your household cash flow doesn't change at all; the overpayment is essentially free money. Cons: requires discipline at each remortgage.
Take an offset mortgage and keep your savings in the linked account. You don't technically "overpay" but you get the same interest-reducing effect, with full liquidity.
Best for: higher-rate taxpayers and self-employed with large cash reserves. Pros: full flexibility, tax-efficient. Cons: higher rate, fewer lenders, cash earns no growth. See our offset guide.
Save aggressively throughout your fix period (in savings accounts and ISAs), then use the end-of-fix window, the 1–3 months before the fix ends, when most lenders waive the 10% cap, to dump everything into the mortgage at once.
Best for: people with big lump sums coming (inheritance, house sale, bonus) who'd otherwise breach the 10% cap. Pros: no ERC risk; the largest possible single reduction. Cons: timing is critical; interest is accumulating at mortgage rates on the mortgage balance the whole time.
For most people most of the time, regular monthly overpayment (Strategy 1) wins on pure maths, compounding from day one beats any lumpier approach. But the "right" strategy is the one you'll actually stick to, which depends on your income pattern and your psychology.
Nothing says you can only pick one. A common high-performer: Strategy 1 (monthly £200 on autopilot) + Strategy 4 (remortgage-and-maintain) + Strategy 6 (any lump sum goes to the fix-end blitz). That combination clears a typical 25-year £250k mortgage in about 15 years with modest extra contributions.
Every strategy here is modelled in the main calculator, enter a monthly figure for Strategy 1 or 3, a lump sum for Strategy 2 or 6, and use the advanced panel to set the ERC and allowance rules. Combine fields to model hybrid approaches.