Overpay mortgage or invest ISA long-term

[ALT72]

I am in my early 50s and up until recently bonds and ISAs rates were pretty poor. My husband and I invested on our property instead by moving to a bigger house with the intention of downsizing in retirement. We locked in on a 10 years fixed rate mortgage 2 years ago right before the interest rates went up. We have a £140k mortgage on 2.25% interest over 20 years (now 18 years left). My question is should we consider overpaying our mortgage of approx £750 pm or open up an ISA Stock and Shares on high risk long-term (possibly 15 years)?

You'd be mad to overpay the mortgage when it's on such a low rate

It's not either/or. You don't HAVE to have a high-risk investment instead of overpaying the mortgage.

You can just stick the equivalent overpayment in an instant access 5% interest account until your fixed rate is up and still be better off.

Well done on that fix!

What other savings and investments do you have? How are your pensions? Retirement plans?

I definitely would not overpay now as you can make more in interest than you are paying on the mortgage. So it would be better to save in cash (or maybe invest in shares) and then pay off a chunk at the end of the fixed term (this is assuming you have no problem making the monthly payments).

The harder question is cash or shares, which depends on your situation more generally and your attitude to risk. Given that you have the fix for 8 years I would probably go for a S&S ISA then when the rate ends you can choose to sell some shares to pay off a chunk- generally the stock market will outperform cash over an 8 year period. But this is not guaranteed, so if you would prefer not to take the risk cash savings might be better.