IGST or Integrated Goods and Services Tax is the GST rate applicable when the freelancer and the client are in two different states.
CGST or Central Goods and Services Tax is the component of GST that the central government collects for sales of goods and services within a state.
SGST or State Goods and Services Tax is the component of GST that the state government collects for sales of goods and services within a state.
The GST Rate for individual freelancers is 18%.
If your client is in the same state, you charge 9% CGST and 9% as SGST. However, if your client is a different state, then you 18% as IGST.