Mortgage overpayment

Interest and time saved by paying extra each month or as a lump sum.

Your details

Your result

Interest you’d save£38,458
  • Interest saved23%£38,458
  • Interest still paid77%£128,416
Normal monthly payment£1,390
Mortgage-free sooner by5 yrs 1 mths
New payoff time19 yrs 11 mths
Overpaying earns the equivalent of4.5% tax-free
Assumptions and limits

Overpaying usually beats saving if your savings rate after tax is lower than your mortgage rate, but keep an emergency fund first, as overpayments are hard to get back. Most fixed deals let you overpay up to 10% a year before an early repayment charge.

Worked out with standard formulasTax year 2026/27

Common questions

Should I overpay or save?

If your savings rate after tax is lower than your mortgage rate, overpaying usually saves more. Keep an emergency fund first, as overpayments are hard to get back.

Should I reduce my payment or my term?

Reducing the term saves more interest; reducing the payment frees up monthly cash. Lenders handle this differently, so ask yours.

How much can I overpay without a charge?

Many fixed deals allow up to 10% of the balance a year. Above that, an early repayment charge may apply.

How we calculate

Every calculator uses the published 2026/27 rates from one shared set of rules, so when a rate changes, it changes everywhere.

Where rates come from

Tax, National Insurance, student loan, benefit and property tax rates come from GOV.UK. Each calculator links to its sources.

What we don’t cover

Scottish income tax bands, tax codes other than 1257L, benefits in kind and your personal circumstances. Results are estimates to help you plan, not a payslip or advice.