There are 3 types of taxes - CGST, IGST and SGST(GST). IGST is on inter State supply..however, SGST and CGST is on intrastate supply (within the state). Therefore, the restaurant bill having 9% CGST and SGST 9% . The effective rate of GST being 18% (which is divided as 50-50 percent. in CGST and SGST)