Free UK mortgage overpayment calculator

🏠 Mortgage Overpayment Calculator UK

See how much time and money you save by overpaying your UK mortgage. Even £100/month extra can save tens of thousands in interest and knock years off your term.

Your mortgage details

£220,000
£10000£1,000,000
25 years
1 years40 years
4.5%
0.5%10%
£200/mo
£0/mo£2,000/mo
Standard monthly payment: £1,223
With overpayment: £1,423

Time saved

5yr 8mo

off your mortgage term

Interest saved

£37,237

by paying £200/mo extra

Without overpayment — total interest£146,849
With overpayment — total interest£109,612
Total extra paid over term£46,400
Net interest saved£0
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Not financial advice. For illustrative purposes only.

Should you overpay your mortgage in the UK?

With UK mortgage rates at 4–6% following recent Bank of England rate rises, overpaying your mortgage has become one of the most powerful risk-free financial moves available to homeowners. Unlike investing, there's no market risk — a guaranteed "return" equal to your mortgage rate.

Most UK mortgage lenders allow overpayments of up to 10% of the outstanding balance per year without an Early Repayment Charge (ERC). Beyond that, ERCs typically apply during fixed-rate or tracker mortgage deals.

Overpaying vs investing: which is better in the UK?

The answer depends entirely on your mortgage rate:

If your rate is above 5%: Overpaying likely beats investing (guaranteed saving vs uncertain 7% average market return after fees and tax)
If your rate is 4–5%: Borderline — consider splitting extra money between overpayment and ISA contributions. ISA tax advantage may tip the balance toward investing.
If your rate is below 4%: Investing in a global index fund via ISA likely outperforms overpaying long-term. Your mortgage rate is below expected real investment returns.

UK Early Repayment Charges (ERCs) explained

An ERC is a penalty charged when you repay more than your lender's allowed overpayment limit, usually during a fixed-rate deal. Typical ERCs are:

  • 5% of the amount overpaid (in year 1 of a 5-year fix)
  • Reducing by 1% per year: 4% in year 2, 3% in year 3, etc.
  • 0% once the fixed-rate period ends (you're on SVR)

Most lenders allow 10% of the outstanding balance per year as fee-free overpayment. On a £200,000 mortgage, that's £20,000 per year — more than enough for most overpayers.

When to remortgage vs overpay

If you're on your lender's Standard Variable Rate (SVR), remortgaging to a new fixed deal almost always saves more money than overpaying — a 1.5–2% rate reduction on a £200,000 mortgage saves £3,000–£4,000/year in interest. Only start overpaying once you're on a competitive rate.

Frequently asked questions

How much can I overpay on my UK mortgage each year?

Most UK lenders allow 10% of your outstanding balance per year without penalty. Check your mortgage offer document or call your lender to confirm your specific limit. Anything above this during a fixed-rate period will trigger an Early Repayment Charge.

Does overpaying a mortgage reduce monthly payments or term?

In the UK, most lenders by default reduce your term (you pay off the mortgage earlier) rather than reduce your monthly payment. If you want lower monthly payments instead, contact your lender to request a recalculation — some allow this.

Is it worth overpaying a fixed-rate mortgage UK?

Yes, up to the 10% annual fee-free limit. Beyond that, wait until your fixed deal ends to avoid ERCs unless the interest savings significantly exceed the penalty cost — use this calculator to compare.

Should I overpay my mortgage or put money in a pension?

Pension (SIPP) contributions come with income tax relief of 20–45% which almost always beats mortgage overpayment savings. If you're not maximising your pension contributions, contribute there first, especially if your employer matches contributions. After maxing tax-advantaged options, direct extra cash to mortgage overpayment.

Track your mortgage overpayments in FinSavvy

FinSavvy's Mortgage Optimiser tracks your overpayments, tells you when to remortgage, and factors your payoff date into your FIRE timeline. Connect your bank and see the full picture.

Start Free — Track My Mortgage →

Not financial advice. Projections for educational purposes only. Consult a qualified mortgage adviser.