Mortgage Overpayment Calculator

A mortgage overpayment is when you pay more than your agreed monthly repayment. The extra amount goes straight towards reducing your mortgage balance, which usually means less interest over time and a shorter mortgage term.

Interest is charged on what you owe. If you reduce the balance earlier, you generally pay less interest overall. Even modest regular overpayments can make a big difference over the life of the mortgage.

Sometimes. Many fixed and discounted deals allow you to overpay up to a set amount each year without an ERC (often expressed as a percentage of the balance), but this varies by lender and product.

Before committing to regular overpayments, check your mortgage offer or online account to confirm your lender’s overpayment allowance and any Early Repayment Charges (ERCs). If your fixed rate is ending soon, it’s worth reviewing your next deal first — your options may affect whether overpaying now makes sense. See our remortgage guide.

It depends on your priorities. Overpaying can reduce long-term interest, but keeping savings can be wise if you need easy-access money for emergencies or upcoming costs.

A common approach is: keep an emergency fund first, then overpay within any ERC-free allowance. If you want a quick sense-check based on your numbers, email us and we’ll help you compare the options.

It depends on your lender and how the overpayment is treated. Some lenders keep the monthly payment the same and shorten the term, while others may recalibrate the payment. If you have a preference, it’s worth checking what your lender does by default.

If the goal is comfort each month, reducing payments might help. If the goal is paying off faster, reducing the term is often the target.

The main risk is triggering an ERC during a fixed-rate period. The second is liquidity — once money goes into the mortgage, it’s not always easy to access again.

If you’re overpaying as part of a bigger “reduce risk” plan, it can also be worth thinking about protecting your income. Explore protection options.