These are the links you will need to read so you can decide for yourself which is correct.
If you go to the RSTU page and look under forms, you will see that there are separate forms for topup using cash and using CPF, but they all fall under the RSTU scheme.
https://www.cpf.gov.sg/Members/Schemes/schemes/retirement/retirement-sum-topping-up-scheme
In the RSTU FAQ, it again talks about transferring from your OA to your SA under the scheme
https://www.cpf.gov.sg/members/FAQ/...ping-Up Scheme&folderid=19860&ajfaqid=2188830
And in the CPF Life FAQ, it states that top-ups made under RSTU is excluded from being withdrawn with a property pledge
https://www.cpf.gov.sg/members/FAQ/...group=CPF LIFE&folderid=11656&ajfaqid=2186359
I think BBCWatcher correctly read my mind.
Maybe I should explain why I said “locked”, my plan is as follows:
1.) SA shielding
2.) FRS at 55
3.) BRS at 65
Assume FRS $181k, then BRS $90.5k.
At 65, if I decide to pledge my property, I will get back cash from my RA as follows:
i) $90.5k if I had only transfer from OA to SA, no cash top-up.
ii) $90.5k minus [all cash top-up]
I assume after CPF refund, the “refunded cash” goes back to OA first, then OA transfer to SA. This “refunded cash” does not fall under “cash top-up”. So it should not reduce the amount that I can withdraw from RA at 65. Thus this “refunded cash” is not “locked”.
Hope I am correct, if not please let me know.
tangent seems to be lost and confused himself, so he asked u to read all the rules to make u more confused

I always write in to CPFB to get double confirmation, cos reading the whole website will not give u a direct or complete answer. Whatever u raised is not new, had been discussed here before. Maybe Uncle Henry can help u further when he is free

