1. Quoting GSTIN in Shipping bill is mandatory if the export product attracts GST for domestic clearance.
2. Quoting PAN (Permanent Account Number), which is authorized as Import Export code by DGFT, would suffice if the exporter exclusively deals with products which are either wholly exempt from GST or out of GST regime.
3. In case of exports by specialized agencies such as United Nations Organization or notified Multilateral Financial Institutions, Embassies and Consulates, the exporter can quote Unique Identity Number, instead of GSTIN, in the Shipping bill.
4. Without GSTIN or PAN or UIN, the Shipping bill cannot be filed.
5. The claim for refund of IGST paid or Input Tax Credit on inputs consumed in goods exported cannot be processed without GSTIN and GST Invoice details in Shipping Bill.
6. Commercial Invoice information should be provided in the Shipping Bill. Wherever Commercial Invoice is different from Tax Invoice, details of both have to be provided in the Shipping Bill.
7. Taxable value and Tax amount should be mentioned against each item in the Shipping bill for processing the refund amount. Multiple tax invoices issued by same GSTIN holder are allowed in one Shipping bill for the same consignee.
8. State code is part of GSTIN numbering scheme. However, in the Shipping Bill for the field “State of origin” declare the State code from where export goods originated as it was being done before.
Source: http://cbec.gov.in/resources//htdocs-cbec/gst/GST%20and%20Exports%20-materail%20for%20advertisement%20v2.1.pdf