Summary This article explains how mortgage overpayments work during fixed-rate periods in the UK, including early repayment charges, lender rules, and common limitations. It is for general information only. Most UK mortgage lenders allow you to overpay your mortgage — but only up to a limit. This is known as the mortgage overpayment cap, and exceeding it can trigger early repayment charges (ERCs). Understanding how this cap works is essential if you want to reduce interest, s