Should You Pay Off Your Mortgage or Invest?

Overpaying your mortgage gives a guaranteed, risk-free return equal to your mortgage interest rate.

Investing has historically delivered higher returns, but those returns are not guaranteed and come with volatility.

The breakeven point is the investment return you need just to match the benefit of overpaying - anything below that and you would have been better off reducing the mortgage.

For most people, the right answer is a blend: clear high-rate debt first, then split spare cash between overpayments and investing in an ISA.