As i know, only corporate tax can do so. That means only those Sdn Bhd/Bhd can use credit to offset instalments. For individual tax, you can't do so because they won't give you approval letter. If you really did not pay the instalment, they will charge you 10% penalty. It's better to pay all the instalments and write letter to ask for refund if overpayment.

you are definitely right! unless you say you have bought shares or unit trust because 28% has been taken while the dividend is declared.