The GST state code is a unique 2 digit code prefixed to the GST Number. Since, the GST number is a 15 digit code, the first 2 digits signifies the state code. The government has allotted unique code to each and every state of India. Thus, every person requiring GST registration shall specify his state while making an application. One can find more about these state from here
https://gstindianews.info/gst-state-code-list-india-download-excel-pdf/
. Thus, on the basis of these codes the government can classify whether IGST OR CGST + SGST/UTGST should be charged to the recipient of goods or services or both.
One can access the complete list of these codes from the above link.
