Asked on 14 Jan 2019
Let me know thank you :)
You have to find out your annual limit. You can only get tax relief on cpf based on the annual limit.
Jan is the best time because it can compound the interest for the whole year and is also the time when last year interest is credited.
I would recommend to do OA-SA transfers only if you will not need those funds for education or housing in the near future since it's irreversible. If you want to qualify for income tax relief you should be considering RSTU to your SA or VC to your MA instead.
Unfortunately, transfering from OA to SA does not have any impact on your income tax. You will need to top up your SA using cash. The maximum CPF Cash Top-up Relief per Year of Assessment (YA) is $14,000 (maximum $7,000 for self, and maximum $7,000 for family members).
And yes, January is the best time to do it so that you can maximise the interest of 4% you can earn for the year.
As mentioned elsewhere - there is no tax relief for shuffling around CPF balances between OA and SA accounts.
On the timing - I think not so important as the interest is calculated based on the monthly balances - so the benefit will kick in the month subsequent to your action. Given the higher interest on SA, if you are going to do this anyway then best to do ASAP rather than waiting for any particular month of the year.
I believe you can only get income tax relief if you actually use cash to top up your CPF SA!
and the limit is up to $14k for personal and $7k for a family member