confusion is setting in here.. just because the agent is charging you a fee that happens to be the same as your rental rate doesn't mean they are charging you rent... they are charging you a fee of $x and GST will apply to that. the fact that you can't charge that GST on to your tenant is part of the joy of resi IP. just bear in mind the big picture, you are after cap gain because your revenues wiull be negligible in this field