When you have to register for GST

You must register for GST:

when your business or enterprise has a GST turnover (gross income from all businesses minus GST) of $75,000 or more (the GST threshold).
when you start a new business. and expect your turnover to reach the GST threshold (or more) in the first year of operation.
if you’re already in business and have reached the GST threshold.
if your non-profit organisation has a GST turnover of $150,000 per year or more.
when you provide taxi or ride sharing travel services for passengers regardless of your GST turnover – this applies to both owner-drivers and if you lease or rent a taxi.
if you want to claim fuel tax credits for your business or enterprise.