The decision between overpaying your mortgage and saving comes down to one number: your mortgage rate vs. your savings rate after tax. Here's the honest breakdown — followed by a calculator that shows what overpaying would do for you.
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.
Overpaying your mortgage gives you a guaranteed, tax-free return equal to your mortgage rate. If you're on 4.8%, every £1 overpaid effectively earns 4.8% — risk-free.
Savings give you interest, but it's taxed if you're over your Personal Savings Allowance (£1,000 for basic-rate taxpayers, £500 for higher-rate). Basic-rate easy-access savings around 4% gross become ~3.2% net once you exceed the PSA.
If mortgage rate (4.8%) > net savings rate (3.2%), overpaying wins on pure maths. The bigger the gap, the more obvious the answer.
Money paid onto a mortgage is locked into your home. You can't get it back without remortgaging or selling. That's why you need an emergency fund first — 3 to 6 months of essential outgoings in an instant-access account.
Beyond that emergency buffer, every additional pound is a choice between overpaying (higher guaranteed return) and saving (instantly accessible).
If you really can't decide, an offset mortgage lets your savings reduce the balance interest is calculated on, without overpaying. You keep access to the cash and reduce mortgage interest at the same time. Rates are slightly higher than standard deals — worth comparing if liquidity matters to you.
Important: This article is for general information and is not financial advice. Always speak to a qualified UK mortgage adviser before making decisions about overpayments, remortgaging, or your specific mortgage product.