One point not mentioned in this thread is that after reaching retirement age, you can withdraw from OA and SA any time (subject to some rules), but you can’t withdraw from RA account. Hence, to the person who asked why not transfer from OA to RA to earn a higher interest, the answer is that if you have more than FRS amount in SA before age 55, it’s best to “shield” some money so that there’s more money in SA (earning higher interest) than in OA even though you can withdraw from both OA and SA.