The GST has been further subdivided into 3 sub-categories. For example, when there is an intrastate sale (within a state) then the GST will be split equally between CGST and SGST. So, if the GST on service is 18% then while preparing the invoice 9% will be payable as CGST and 9% will be payable as SGST, which will be apportioned equally between the centre and the state. However, the treatment is slightly different in case of interstate sales. For example, if your business is based in Mumbai and you sell to a customer in Chennai, then it becomes an inter-state sale and will attract IGST at the full rate prescribed.