Mortgage overpayments · illustrative figures
Mortgage overpayment calculator
What paying extra does to your mortgage, monthly or as a lump sum.
See when you’d be mortgage-free, and what overpaying saves. Illustrations, not advice.
Assumes a repayment mortgage at this rate throughout, and that your lender shortens your term. See a lower payment instead
Mortgage-free by July 2043. £33,723 less interest, and 5 years 3 months sooner than October 2048.
Plate 05 The Rule
The years along the rule; the ones you no longer pay fall away
Your home may be repossessed if you do not keep up repayments on your mortgage or any other debt secured on it.
What this means for you
What this means for you
You’d pay £1,564 a month instead of £1,314, and the mortgage would be paid off after 201 payments instead of 264. Across those payments the interest comes to £93,239, against £126,962 if you carry on as you are.
That’s £3,000 of overpayments in the first year, inside a 10% allowance of £22,000.
How we calculate this
How we calculate this
How are mortgage overpayments calculated?
- Your payment
- The standard repayment formula for what you owe, your rate and the years left.
- Month by month
- Each month’s interest is the balance × your rate ÷ 12. Your payment and any overpayment come off the balance. The last payment is only what’s left.
- Lump sum
- Comes off the balance in the month you pay it, before that month’s interest.
- A lower payment
- Where your lender lowers your payment instead, we recalculate it monthly after an overpayment, over the term left. Some lenders recalculate once a year, so their figures would differ a little.
- Not included
- Rate changes, fees, interest-only and offset mortgages, and any early repayment charge (the allowance section shows when one could apply).
Figures are illustrations from October 2026, not an offer or a recommendation. Your lender’s figures are the ones to rely on.
I · What it saves
How much will overpaying save me?
In this example, £33,723 of interest, and the mortgage is paid off 5 years 3 months sooner: in July 2043 instead of October 2048.
An overpayment comes straight off what you owe, so from the next month the interest is charged on a smaller balance. That is where the saving comes from, and why an overpayment made early in the term saves more interest than the same amount made later.
What you owe, year by year
The figures, year by year
| End of | Owed, as now | Owed, overpaying | Interest saved so far |
|---|---|---|---|
| Oct 2027 | £214,006 | £210,944 | £63 |
| Oct 2028 | £207,737 | £201,471 | £266 |
| Oct 2029 | £201,180 | £191,564 | £617 |
| Oct 2030 | £194,322 | £181,201 | £1,121 |
| Oct 2031 | £187,149 | £170,363 | £1,786 |
| Oct 2032 | £179,646 | £159,026 | £2,620 |
| Oct 2033 | £171,799 | £147,169 | £3,630 |
| Oct 2034 | £163,591 | £134,767 | £4,824 |
| Oct 2035 | £155,006 | £121,795 | £6,211 |
| Oct 2036 | £146,026 | £108,227 | £7,800 |
| Oct 2037 | £136,634 | £94,036 | £9,599 |
| Oct 2038 | £126,811 | £79,193 | £11,618 |
| Oct 2039 | £116,536 | £63,668 | £13,869 |
| Oct 2040 | £105,790 | £47,430 | £16,360 |
| Oct 2041 | £94,549 | £30,446 | £19,104 |
| Oct 2042 | £82,792 | £12,681 | £22,111 |
| Oct 2043 | £70,496 | £0 | £25,364 |
| Oct 2044 | £57,634 | £0 | £28,273 |
| Oct 2045 | £44,181 | £0 | £30,591 |
| Oct 2046 | £30,110 | £0 | £32,292 |
| Oct 2047 | £15,393 | £0 | £33,346 |
| Oct 2048 | £0 | £0 | £33,723 |
II · Sooner, or lower
Pay off sooner, or pay less each month?
Lenders differ: some shorten your term, some lower your payment, and some let you choose.
Your lender shortens your term
The payment stays the same; the end date comes forward.
- Interest saved
- £33,723
- Mortgage-free
- July 2043
- Each month
- £1,564
Your lender lowers your payment
The end date stays about the same; the regular payment falls.
- Interest saved
- £18,160
- Mortgage-free
- August 2048
- Regular payment after a year
- £1,296
In this example, a shorter term saves £15,563 more interest; a lower payment leaves you £18 a month more to spend after a year. Both assume your rate stays at 4.50%.
III · The allowance
How much can I overpay without a charge?
While your deal lasts, often 10% of what you owe each year, though it could be less or more. Your mortgage offer says what yours is.
Indicative: what applies to you depends on your mortgage. Overpayment allowances and early repayment charges: HomeOwners Alliance, “Early repayment charges and how to avoid them”, checked October 2026.
On your mortgage offer or annual statement.
Of the balance at the start of each year. Many lenders work it out that way; some use the original loan.
Typically between 1% and 5% (HomeOwners Alliance, checked October 2026). Yours is on your offer.
You’d overpay £3,000, inside the allowance, with £19,000 to spare.
You’d overpay £3,000, inside the allowance, with £18,094 to spare.
After your deal ends, if you move to your lender’s standard variable rate, there’s typically no early repayment charge (HomeOwners Alliance, checked October 2026).
Leaving your deal early is a different question. Is it worth leaving early? →
IV · When your deal ends
Overpay, or remortgage when your deal ends?
Over the five years after your deal ends, here’s how the options compare.
What you’d pay if you did nothing when your deal ends.
The rate you’ve been offered, or one you’re considering.
The same figure as above. Changing it here changes it there.
Bank of England averages are market figures, not offers: the rate you’re offered depends on your circumstances and the lender’s criteria.
Interest
£61,882
You’d still owe £172,656
Interest
£59,177
You’d still owe £154,951
Interest
£46,250
You’d still owe £168,078
Interest
£44,257
You’d still owe £151,085
Payments, rate changes and what’s not included
Monthly payment from your deal’s end: £1,512 on the SVR, £1,327 at 4.98%, before any overpayment.
A fixed rate holds your payment for the fix: if rates fall, you won’t benefit until the fix ends; if they rise, you’re protected. A standard variable rate can go up or down at your lender’s discretion.
Not included: on a new deal, legal fees of £300–£500 and product or arrangement fees of £0–£1,500 (from the lenders we work with, checked October 2026), and any exit fee, up to £300 (HomeOwners Alliance, checked October 2026). Not a recommendation.
V · Questions
Mortgage overpayment questions
How do mortgage overpayments save money?
Overpayments reduce your outstanding balance, so less interest accrues over the life of the loan. That can shorten the term, lower your payment, or both, depending on your lender, and it cuts the total interest you pay.
How much does a lump sum overpayment save?
It depends on the amount, your rate, the years left and when you pay it: the earlier you pay it, the longer the interest is charged on a smaller balance. As an illustration, £10,000 paid now off a £220,000 repayment mortgage at 4.50% with 22 years left saves £15,931 of interest, and the mortgage is paid off 1 year 7 months sooner, if your lender shortens the term. You can pay a lump sum if your lender accepts it; while your deal lasts, it counts towards your yearly overpayment allowance together with any regular overpayments.
Should I overpay my mortgage or save the money instead?
It depends on your mortgage rate against what your savings would earn, whether you have more expensive debt, and whether you need money you can reach. If your mortgage rate is higher than your savings rate after tax, an overpayment saves more than the savings would earn; if it’s lower, the reverse. Money you overpay generally can’t be taken back out, unless your mortgage has a borrow-back feature. For the tax side, speak to an accountant.
Can this calculator work out an early repayment charge?
Yes, for overpayments. While your deal lasts, an early repayment charge usually applies only to the amount you overpay above your yearly allowance, which is often 10% of what you owe. The charge is typically 1% to 5% of that excess (HomeOwners Alliance, checked October 2026), so £6,000 over the allowance at 3% would be £180. Enter your deal’s end, your allowance and your charge from your mortgage offer, and the calculator works it out year by year. For the charge on leaving your deal early to remortgage, use the remortgage calculator.
Is there a limit on how much I can overpay?
Usually, while your deal lasts. An overpayment allowance is often 10% of the balance a year, though it could be less or more (HomeOwners Alliance, checked October 2026). Above the allowance, an early repayment charge may apply to the amount over it. Your mortgage offer sets out what applies to you.
Does overpaying reduce my term or my monthly payment?
Lenders differ: some shorten your term, some lower your payment, and some let you choose. A shorter term saves more interest; a lower payment leaves you more each month. This calculator shows both for your figures.
Can I overpay on a standard variable rate?
Generally, yes. Standard variable rate mortgages typically come with no early repayment charge (HomeOwners Alliance, checked October 2026), so an overpayment allowance does not usually apply. Check with your lender before you pay.
Does this calculator work for an interest-only mortgage?
Not as it stands: it assumes a repayment mortgage. On interest-only, an overpayment lowers the balance, so the monthly interest falls, but what’s left is still due at the end of the term. We can work through your figures with you.
Is it worth overpaying before I remortgage?
Overpaying lowers what you owe when your deal ends, which with some lenders can move you into a lower loan-to-value band. Inside your deal, the overpayment allowance still applies. This calculator compares overpaying with moving to a new deal for your figures.
Read and plan further
Next
Talk your figures through with Nathan
Nathan handles your case personally. Your figures go with your booking, so the call starts from your numbers: what you owe, your deal and allowance, and what a new rate would do.
No credit check · no obligation
What Nathan will see with your booking
What Nathan will see with your booking
From the overpayment calculator Owe £220,000 at 4.50%, 22 years left Overpaying £250 a month Mortgage-free July 2043 (5 years 3 months sooner) · interest saved £33,723 Deal ends in 2 years · allowance 10% a year: within it Compared at deal end: SVR 6.58% and a new rate of 4.98%, over 5 years
You can edit or delete this on the booking page before you send it.
Our standard fee is £495, payable when your application is submitted. In some more complex cases, an additional broker fee of up to 1% of the loan may apply. The first conversation is always free, and we always confirm your total fee in writing before any work starts.
Your home may be repossessed if you do not keep up repayments on your mortgage or any other debt secured on it.