If you invest in a Stocks and Shares ISA the financial risk is higher than a standard repayment mortgage, but it can also be a faster method of repayment.
With an ISA mortgage you pay only the monthly interest on your mortgage, with the rest of the money going into an investment ISA. The aim is to raise a lump sum large enough to pay off the mortgage in full after a number of years. An ISA mortgage can provide a preferable rate of repayment in many cases, but this comes with the possibility of encountering a shortfall if your investment performs poorly.
Those engaging with an ISA mortgage should keep a close eye on their investment and its performance, seeking to ensure the returns meet the needed amounts. If you are unsure what to do you should seek independent financial advice.