Mortgage Overpayment Case Study

Starting assumptions

The example uses a £180,000 repayment balance, 20 years remaining and a constant 4.5% illustrative rate. It compares the scheduled payment with an extra £150 each month.

What the calculator models

Each month it applies interest to the outstanding balance and then reduces capital by the payment. The extra amount reduces capital sooner, which can reduce later interest if the assumptions persist.

What changes the answer

Rate changes, missed payments, a different payment date and lender calculation conventions can alter the outcome. Results should be treated as scenarios, not promises.

Contract checks

Confirm any annual or monthly overpayment allowance, early-repayment charge, minimum amount and how the lender applies an extra payment. Ask whether it reduces term, future payment or both.

Liquidity check

Money paid into a conventional mortgage may not be readily recoverable. Compare the potential interest saving with emergency reserves, expensive debt and other commitments.

Acceptance method

Compare the first month's interest and capital manually, retain the assumptions and ask the lender for an updated illustration before acting on a material decision.