GST is applicable when u started fall in anyone below category:

1. Any business involved in the supply of goods whose turnover in a financial year exceeds Rs.40 lakhs for Normal Category states
2. Any business involved in the supply of services whose turnover in a financial year exceeds Rs.20 lakhs for Normal Category states
3. When a business which is registered has been transferred to someone/demerged, the transferee shall take registration with effect from the date of transfer.
4. A person making inter-state supplies
5. Those paying tax under the reverse charge mechanism
6. e-Commerce operator
7. Person who supplies via e-commerce aggregator