Overpayment calculator
Overpaying attacks the balance directly, so every pound reduces the interest charged for the whole remaining term. Small, consistent overpayments compound into surprisingly large savings — but check your deal's annual limit before you start.
Why overpaying works so hard
Answer first: because interest is charged on the balance, and an overpayment reduces that balance permanently. The saving is not just this month's interest — it is the interest that pound would have generated every remaining month of the term.
That is why overpayments made early are worth considerably more than the same amount made near the end. The effect compounds, and it is the reason a modest monthly sum can knock years off a term.
The limit to check first
Most fixed and tracker deals allow overpayments up to a set percentage of the balance each year, commonly around 10%. Exceed it and you can trigger an early repayment charge, which will comfortably undo the benefit.
So before setting up a standing order, confirm your allowance and how your lender measures it — some run it on the calendar year, some on the anniversary of the deal. On a standard variable rate there is normally no limit at all, though if you are on an SVR your first priority should be leaving it rather than overpaying it.
Overpay, or put the money elsewhere?
A fair question, and the answer is not automatic. Overpaying gives you a guaranteed return equal to your mortgage rate, which is genuinely attractive when rates are high. But the money becomes hard to access — it is in the house, not in your account.
For a contractor with income that arrives unevenly between contracts, that liquidity point carries real weight. An offset mortgage is worth comparing here: it cuts interest in much the same way while leaving the cash available, which suits lumpy income. Offset for directors covers the company-cash version.
Overpayment, answered
How much can I overpay without a penalty?+
Most deals allow up to a set percentage of the balance each year, commonly around 10%, though it varies by lender and product. Beyond that an early repayment charge usually applies. Check your offer document or ask your lender before setting up regular overpayments.
Is it better to reduce the term or the payment?+
Reducing the term saves more interest, because you keep paying the same amount against a falling balance. Reducing the payment gives you monthly breathing room instead. Many lenders let you choose; some apply overpayments to the term by default.
Should I overpay or save the money?+
It depends on your rate, your access to savings, and how stable your income is. Overpaying returns your mortgage rate risk-free, but locks the money into the property. If your income varies between contracts, keeping a cash buffer — or using an offset — may matter more than the interest saved.
Do overpayments reduce my monthly payment straight away?+
Not usually. Unless you ask the lender to recalculate, the payment normally stays the same and the term shortens instead. That is the more efficient outcome, but if you want a lower monthly cost you need to request it explicitly.