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E-Invoicing Under GST: Applicability, IRN & QR Code Rules

Businesses above ₹5 crore turnover must generate IRN for B2B invoices. Learn what changes on your invoice and how to stay compliant.

24 May 2026 7 min readBy SmartGST Team
E-Invoicing Under GST: Applicability, IRN & QR Code Rules

Who must e-invoice

All registered persons with aggregate turnover above ₹5 crore in any financial year from 2017-18 onwards, for B2B supplies, exports and supplies to SEZ. B2C invoices are exempt (but need a dynamic QR above ₹500 crore).

What is IRN

The Invoice Reference Number is a 64-character hash generated by the Invoice Registration Portal (IRP) when you upload the invoice JSON in the prescribed schema (INV-01).

The 30-day rule

For taxpayers above ₹10 crore, invoices must be reported to the IRP within 30 days of the invoice date, else they are rejected.

What the printed invoice must show

The IRN, the signed QR code from the IRP and the acknowledgement number and date. Without these the document is not a valid tax invoice.

Generate the JSON instantly

SmartGST exports an IRP-ready e-Invoice JSON from any invoice, so you only need to upload it to the portal or your GSP.

Try it on your next invoice

SmartGST Invoices automates GST calculation, HSN codes, reminders and GSTR reports. Free to start.

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Keywords: e invoicing applicability · irn qr code invoice. This article is general information, not professional tax advice.