I dont know about current promo rate frm OCBC, but their approach is different .. they dont open new account like CIMB. They are the worst of the BT ...
example : BT 12K
1 time upfront charge 3% (depending on pkg) = RM360.. then 0% for the BT period
when receive stmt :-
u will be billed RM360
if no merchant transaction, then total outstanding = RM12,360. Minimum pymt = RM618. When u make pymt, the RM360 is NOT PAID off .. (only paid 5% of it = RM18,,,, balance of RM342 kena charged normal int), even if pay more also will go towards BT amount.
But if got merchant transaction, then DAMN confusing.....the payment hierarchy is 5% minimum on TOTAL balance... you will NEVER be able to pay off the merchant transactions (since no separate account for BT and merchant transaction), so in the above example, if your merchant transaction is RM2000, then
balance = RM12,360 + 2000 = RM14,360... min pymt = RM718 ... the balance is RM13,642
breakdown :-
RM11,400 = BT balance = 0% intrest
RM342 = BT charge ost = 17.5% int
RM1900 = merchant trans ost = 17.5% int
If pay more than minimum payment, the extra will payoff the BT balance.... NOT the merchant or BT charge....
so if wanna use OCBC, then B4/after BT, DONT USE it for merchant transaction ....
Damn confusing? lol ..... no lar

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This works for most of the bank...as long no separated account created for your BT, then any merchant transaction made with the same card that hold your BT, the payment you made will deduct the BT first....if you made any purchase, say, 1K..imagine the interest you need to pay for the 1k interest every month...you will be charge for interest for that 1k as long your BT is not fully paid...