How often you need to lodge a BAS depends on your turnover and whether or not you’ve voluntarily registered for GST.nYou will need to lodge:nAnnually: if you’ve voluntarily registered for GST and your turnover is under $75,000 or $150,000 for not-for-profit organisationsnQuarterly: GST turnovers under $20 millionnMonthly: GST turnovers of $20 million or more