My housing loan is 1.5k, i need contribute $2.6k a month.
Ordinary Account
$1,476.02 <----
Special Account
$491.66
MediSave Account
$632.32
And those i contribue $1.5k x 12months x MOP 5 years = $90k
So that means i have to return back 2.5% of 90k (5 yrs) will be $11k of interests.
A bit not worth... for now i have to contribute $500 a month to medisave.
There's a bit more to it.
I believe you're in the 7% tax bracket, so your Voluntary Contributions (VCs) to CPF should be eligible for 7% tax relief. But let's assume you "only" net 5% of income tax savings on the additional VCs (above your existing $6,000/year to MediSave). That means you'd cut your income tax bill by about $1,200. If your income increases then you could be pushed into a higher tax bracket and save more on your income tax bill.
Then there's the fact your Special Account contributions will earn at least 4%, possibly 5.01% if you're still in bonus interest territory. That's a very good deal!
The accumulated interest (2.5%) on your Ordinary Account is simply paying yourself back. You don't lose that money. It goes back into your OA where you can use it again for housing. (And wouldn't you need money for housing if you sell your HDB flat? Or do you plan to rent or live overseas after the MOP?) Also, once you're age 55+ you may have the option of taking the full sales proceeds from the home as cash if you wish. (If you've adequately funded your Retirement Account you would have that option.)
Understand the special account is for retirement but u have my own other retirement plans
So do I, but this is a deal I'd take. The attractive interest, tax relief, and asset protection aspects of CPF are hard to beat. (Self-employed individuals tend to run greater risks in terms of liabilities and asset depleting calamities. CPF assets are well protected against such unfortunate events.)
The "real" math is that you have to contribute $500/month into MediSave anyway. That would be about $2,056 per month if you make VCs consistent with your obligatory MA, of which about $389 lands in your Special Account. So can you come up with $389/month more per month (beyond your mortgage payment) that goes into an attractive account for your retirement, and with tax relief and asset protection? Your mortgage payment can be any blend of cash and OA you wish. The additional tax relief (5% assumed) would be about $934 per year — equivalent to about 2.4 of those $389/month SA contributions. Not bad!