The query that the OP & other people are asking is very valid. Basically you'll need TFN before March so go to your local ATO and apply for one. Usually if all goes well, you should get one in a week. Don't worry about your offer lapsing, because by the stage you have gotten up to (i.e. HECS-HELP form), you have already confirmed that the offer has been accepted. All you need to worry about is your Semester 1 unit of study enrolments. And besides last day to enrol is March 15 lol, plenty of timeWell, is it ok if I leave the tax file number box blank and just continue with the application then go back and alter it (or call UNSW) when I recieve the tax file number?