What if I overpaid my mortgage every month?
A small regular overpayment quietly chips away at your mortgage balance — reducing the interest you're charged and shortening your term. Move the sliders to see the illustrative difference.
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Overpaying by £200/month on a £250,000 mortgage at 5% could save around £27,400 in interest and mean you're mortgage-free more than 4 years early. Check your lender's overpayment policy — most allow up to 10% of the balance per year without penalty.
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How does mortgage overpayment work?
When you overpay your mortgage, the extra amount reduces your outstanding balance immediately. Because interest is calculated on the remaining balance, a smaller balance means less interest charged the following month — and every month after. The effect compounds quietly but powerfully over time.
Most UK lenders allow overpayments of up to 10% of the outstanding balance per year without an Early Repayment Charge (ERC). Always check your mortgage terms before overpaying. This calculator assumes no ERC penalties and a repayment (not interest-only) mortgage.
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Illustrative purposes only. This calculator uses a standard mortgage amortisation model. It assumes a fixed interest rate throughout the term and that all overpayments reduce the capital balance immediately. It does not account for ERC penalties, product fees, rate changes, or lender-specific overpayment policies. Not financial advice. Consult an FCA-authorised mortgage adviser for personalised guidance.