Though I’m no CPF expert, I’ll try my best to clear your doubts:
Case 1: Yes, the balance unused portion goes to your kids if you have nominated them as the beneficiaries (including the unused annuity premiums net off interest earned on the annuity premiums).
Please nominate your kids as beneficiaries if you haven’t done so.
https://www.cpf.gov.sg/Assets/Members/Documents/FORM_6A1_CASH.pdf
Case 2: Yes, if you live till 101, there will be nothing left to bequest (you have already taken back a lot more than what you had contributed).
Look at the “your bequest over time” chart for all 3 plans.
https://www.drwealth.com/cpf-life/
The “maintenance”is paid by other CPF Life members that did not live that long. This is called risk-pooling (all insurance companies that provide annuity policies do this).
Is it “sustainable”? Why not?
In case 1, they are just returning your money as a bequest.
In case 2, should mortality rates drop (everyone lives longer) compared to the actuarial calculation, they can raise the lifelong income fund premiums for future cohorts.
I see. Thanks for clarifying. Which leaves another piece of doubt for me.
Case 1: i choose basic sum and die at age 66. Balance will go to my kids right?
Case 2: i choose basic sum but i live till 101 years old, so i will be eating up way more than what i put in (inclusive interest) and so i don't have anything to bequest for my kids. Right?
Looking at both cases i wonder how the govt upkeeps the "maintenance"? 1st case they dont earn and 2nd case they lose money. Is this sustainable?