Is it better to overpay your mortgage or save?
Compare your mortgage rate with your savings rate after tax, with a worked example. A plain-English guide for UK homeowners.
By Asis Tewari Published · Last reviewed · 2 min read
The short answer
Compare your mortgage rate with the interest you would actually keep on savings after any tax. If your savings rate after tax is lower than your mortgage rate, overpaying usually saves more, but the money is then tied up in your home. Savings stay easy to reach. Most people keep an emergency fund in savings before overpaying.
Key takeaways
- Compare your mortgage rate with your savings rate after any tax on interest.
- Overpaying usually saves more when your mortgage rate is higher, but the money is hard to get back.
- Keep an emergency fund in easy-access savings first.
What does overpaying your mortgage give you?
- A guaranteed saving on interest, at your mortgage rate, for as long as that rate applies.
- A smaller balance, which can mean paying off sooner or paying less each month, depending on your lender.
- A trade-off: money paid into your home is harder to get back out.
What does saving give you?
- Money you can reach quickly if something goes wrong.
- Interest, which may be taxable if it goes over your Personal Savings Allowance. Interest in a Cash ISA is tax-free.
- A trade-off: if your savings rate after tax is lower than your mortgage rate, the gap costs you money each year.
How do you compare your mortgage rate with your savings rate?
Look at the interest you would keep, not the headline rate. If you pay tax on savings interest, your real return is lower than the advertised rate. Then compare it with your mortgage rate. The bigger the gap in favour of your mortgage rate, the more overpaying is likely to save.
How much interest is tax-free depends on your tax band:
| Income Tax band | Personal Savings Allowance |
|---|---|
| Basic rate | £1,000 |
| Higher rate | £500 |
| Additional rate | £0 |
What does this look like in pounds?
For illustration only, say you have £50,000 and a mortgage rate of 4.5%.
- Overpaying: you save £2,250 a year in mortgage interest.
- Saving at 4.5%, as a basic rate taxpayer: you earn £2,250 in interest. The first £1,000 is tax-free. Tax at 20% on the other £1,250 is £250, so you keep £2,000.
In this example, overpaying saves about £250 a year more than savings keep. A higher rate taxpayer would keep less, because their allowance is lower and their tax rate is higher.
What should you ask yourself before you decide?
- Do you have an emergency fund you could reach quickly?
- How does your mortgage rate compare with your savings rate after tax?
- How long until your fixed rate ends, and what can you overpay without a charge? How much can you overpay your mortgage each year?
- Would you rather have the certainty of a smaller mortgage or the flexibility of cash?
Is investing a third option?
Some homeowners also consider investing spare cash, which may grow more over the long term but can fall in value. Read should I overpay my mortgage or invest? to compare. Capital at risk on anything invested.
Tax treatment depends on the individual circumstances of each client and may be subject to change in future.
Sources
- MoneyHelper: Should you pay off your mortgage early? (accessed 3 October 2026)
- GOV.UK: Tax on savings interest, how much is tax-free (accessed 8 October 2026)
Mortgage decisions, made clearer
Get occasional insights on overpayments, investing and fixed-rate changes, without the jargon.
This guide is for information only and is not personal advice. Tax treatment depends on your individual circumstances and may change. If you invest, your capital is at risk. The value of investments can go down as well as up, and you may get back less than you invest. Your home may be repossessed if you do not keep up repayments on your mortgage.