Non-GST invoices and GST payment

Invoice Compliance: A domestic service provider cannot continue issuing non-GST invoices after crossing the ₹20 Lakh threshold. They must apply for registration within 30 days and eventually issue Revised Tax Invoices for the interim processing period.

Retrospective Tax Demand: Yes, the supplier can demand the tax retrospectively. Section 31(3)(a) allows them to issue revised invoices within 1 month of getting their registration certificate to regularize past transactions.

Compelling the Exporter: The GST department holds the supplier liable, not the recipient. However, the exporter should commercially pay the retrospective tax only if the supplier provides a valid Revised Tax Invoice that allows the exporter to successfully claim Input Tax Credit (ITC) and a subsequent export refund.