This what i understand from loan officer below.


If it full flexi, you may place it at current account to reduce interest. This is an example in link below how it helps to reduce your daily interest daily.

https://www.hlb.com.my/en/personal-banking/...tgage-plus.html

for some bank which do not have separate current account. Then they deposit directly into loan account. Same concept.

If you insist on advance payment direct on loan account (reduce principal) Then you must only do it through counter. Otherwise, i think additional amount on monthly installment does not goes to reduce interest or principal. It will just collecting there and auto-deduct for next installment.