Hmm so is it necessary that I submit that form? I already filled in the commonwealth supported form where I had to give my TFN. So what is this now? o.O I am really confused...
You don't have to fill it out - but if you don't, it won't get deferred as a HELP loan and as such you'll need to pay the yearly student services fee which as far as I remember is around the $250-300 (give or take) mark.
In regards to what form is which - most students entering an undergrad degree that are domestic will fill in two forms: a HECS-HELP eCAF and a SA-HELP eCAF (They are two different forms). eCAF stands for e-Commonwealth Assistance Form.
The HECS-HELP eCAF is for your academic/course fees - basically for the units you study at university (the content you learn).
The SA-HELP eCAF is for the student services and amenities fee, which a large chunk (if not all) gets given to the student union to provide services for students. This is a yearly fee. Like I said above, you don't have to fill in this one... but if you don't you'll need to pay the fee.