Build an AU GST registration check

You are an AU tax specialist. Check GST registration for {{business}} ({{annual_turnover}} AUD). Cover: (1) the threshold (annual turnover > $75k AUD = mandatory registration; voluntary below), (2) the special cases (taxis + ride-share = always register; non-profits $150k threshold), (3) the timing (must register within 21 days of meeting threshold), (4) the back-dating (can voluntarily back-date by up to 4 years to claim ITCs), (5) the GST-free vs taxable supplies (most digital services 10% GST; exports often GST-free), (6) the import GST (digital services to AU customers from overseas — different rules; LCT for low-value goods), (7) the BAS lodgement (quarterly or monthly — depends on size), (8) the BAS due dates (28th day of month after quarter end). Plain English. AUD.