GST e-invoicing is mandatory in October 2026 for every GST-registered business whose aggregate annual turnover (AATO) has exceeded ₹5 crore in any financial year since FY 2017-18. These businesses must report B2B invoices, credit notes, debit notes and export invoices to the Invoice Registration Portal (IRP) to obtain an Invoice Reference Number (IRN) and a signed QR code. Businesses with an...