Is it mandatory to plan the return trip in advance when leaving Australia (NSW) for 3 months? I ask because airport staff makes it look like there's a law or something without explaining further details.
If so, why, and how can you be exempt from this regulation?
Edit: Trip is to Germany.
Edit: As comments and replies suggest this is the wrong question. I explained the details in the comments myself. The whole situation has been miscommunicated to me.