Every UK high-street lender lets you overpay around 10% a year fee-free during a fix — but the small print differs in one critical way: some cap you at 10% of the original loan amount (like Nationwide and TSB), others at 10% of the outstanding balance (like Halifax, Santander, Barclays, NatWest, HSBC, Lloyds and Virgin Money). Over a 25-year mortgage that difference can be tens of thousands of pounds. Compare them below, then run your numbers.
Standard fixed and tracker products. Always confirm against your own mortgage offer.
| Lender | Annual cap | Cap basis | Reset window | ERC on excess | SVR cap | Lump-sum credit |
|---|---|---|---|---|---|---|
| Halifax | 10% | Outstanding balance | Calendar year | 1–5% on excess | Unlimited | 1 working day |
| Nationwide | 10% | Original loan | Calendar year (newer deals) | 1–5% on excess | Unlimited | Same / next day |
| Santander | 10% | Outstanding balance | Calendar year | 1–5% on excess | Unlimited | Instant via app |
| Barclays | 10% | Outstanding balance | Calendar year | 1–5% on excess | Unlimited | 1 working day |
| NatWest | 10% | Outstanding balance | Calendar year | 1–5% on excess | Unlimited | 1 working day |
| HSBC | 10% | Outstanding balance | Calendar year | 1–5% on excess | Unlimited | 1 working day |
| Lloyds Bank | 10% | Outstanding balance | Calendar year | 1–5% on excess | Unlimited | 1 working day |
| TSB | 10% | Original loan | Calendar year | 1–5% on excess | Unlimited | 1 working day |
| Virgin Money | 10% | Outstanding balance | Calendar year | 1–5% on excess | Unlimited | 1 working day |
Highlighted rows cap overpayments at 10% of the original loan, which stays generous as your balance falls. All other lenders cap at 10% of the outstanding balance, which shrinks over time.
You'll be mortgage-free 6 years 9 months earlier
and save £46,940 in interest.
| Without | With overpay | |
|---|---|---|
| Term | 25 years | 18 years 3 months |
| Total interest | £156,277 | £109,338 |
| You save | £46,940 · 6y 9m |
A lower interest rate could save you thousands more on top. See if you could remortgage to a better deal.
We may receive a commission if you remortgage through a partner broker. This never affects the rate you're offered.
A 10% cap on the original loan stays fixed for the life of the deal. Borrow £250,000 and you can always overpay £25,000 a year fee-free, regardless of how much you've already paid down.
A 10% cap on the outstanding balance shrinks every year as you pay the mortgage down. On the same £250,000 loan, year-one cap is £25,000 — but once you owe £180,000, the cap is £18,000.
If you plan large overpayments later in the deal, an 'original loan' lender (Nationwide, TSB) is more generous. If you front-load overpayments in year one, the rules are effectively identical.
Every major UK lender charges an ERC if you overpay above the annual allowance during a fix. ERCs are usually 1%–5% of the amount over the cap, tapering down as you approach the end of the deal (e.g. 5% in year one of a 5-year fix, 1% in year five).
ERCs only apply to the excess — not the entire overpayment. Going £2,000 over a £25,000 cap on a 3% ERC costs £60, not £750.
Once you roll onto the lender's Standard Variable Rate (SVR), almost all UK lenders drop the cap entirely — you can clear the mortgage in full with no ERC.
Every lender in this comparison defaults to reducing the mortgage term while keeping your monthly payment the same. That's the option that saves the most interest, by a wide margin.
You can ask any of them to reduce your monthly payment instead — but doing so cuts your interest saving roughly in half versus keeping the term shorter.
Lump sums via app or online banking are typically credited within one working day, so interest savings start straight away.
Nationwide and TSB stand out for capping on the original loan amount — giving steady headroom through the deal.
Santander, NatWest and HSBC offer instant or same-day crediting of lump sums via app, which is useful for end-of-tax-year overpayments.
All the lenders compared here allow unlimited fee-free overpayments on their SVR — so if you're patient enough to wait out a fix, no one charges you.