My father has used up his OA to pay for housing, but has a sum of money left in his SA. What can he do with this sum of money? Can they be invested?

Hi Anon, CPF SA gives all of us a 4% risk free rate. Which is impossible to get in this climate.

So take the 4% and run. If you invest you're taking on risk, may not beat 4% return and may also lose money. Since he's older, there is no reason to take risk.

I would recommend that you advise your dad more on the structure of CPF, and soon CPF Life where he'll receive a monthly income based on the amount he sets aside at age 55 in his Retirement Account.

Consider topping up his CPF SA, or pay housing loan with cash and transfer OA to SA to get even higher optimised returns.

If he still wants to invest, use cash and not his CPF.