SGST on supply of service

SGST is not a replacement of VAT. It is replacement of excise, vat and service tax, and few other state taxes. At present, service tax applies on all services which is collected by Central Government. After GST, GST will be collected by both Central Government and State Governments. The rates are finalised accordingly and no additional burden would be there on services or goods.

CGST and SGST are just the parts of total GST levied under GST law... there are no one-to-one taxes replaced by earlier taxes...

no one to one taxes will be replaced by earlier taxes. both cgst and sgst are part of gst