My mum is 49yo this year and is a kitchen helper earning around 1.8k per month before cpf deduction. OA - 11K, SA - 13K, MA - 12K Currently paying 711 for house with 15 years left (110k). What to do?

I hope you did not convert, now bank rates are like 4%

Disclaimer: I'm not a financial advisor. Just a normal human being. So I may not know best.

Mortgage loans with banks should be having a low interest now (like 1.5% p.a?) but they may not stay low for 15 years.

Banks don't refinance mortgage loans with < $100,000 balance, which means once you do the switch, you cannot refinance to get a lower interest rate.

In a couple of years, when the pandemic dies down, interest rates are likely to rise, and may even rise unpredictably.

On the other hand, while the HDB loan has a higher interest rate, it guarantees one thing: Stability. So, you have to ask your parents if they are able to withstand less predictable interest rates.

As for CPF, I advise against topping up unless there is really some spare cash lying around after saving up x months of emergency savings. In this current situation, x may need to be a higher number, like, 12.

If you do have that spare cash and you are fine with not touching it at all, feel free to top up OA to $20,000 (but this is via the 3-account top-up, which means every dollar into CPF = x cents into OA where x is less than a dollar).

Schemes like Medisave top-up and RSTU are tax-deductible but your mother's income tax should be close to zero, so there is little incentive to do them... Also, RSTU monies are "reserved" and will never see the light of day unless in the form of CPF LIFE annuities which will not happen at least in the next 16 years for your mother.

Last but not least, rushing to pay off mortgage loans is dangerous because you don't ever want to be in a situation where you have a paid home (i.e. illiquid) but with no spare cash to pay emergency bills.

All the best!