e-Invoicing under GST

What is e-invoicing under GST?

e-Invoicing (electronic invoicing) under GST is not a separate type of invoice — it is a reporting system. You continue to issue a regular GST invoice to your buyer, but before (or immediately after) issuance, you must register the invoice on the government's Invoice Registration Portal (IRP). The IRP validates the invoice data, assigns a unique Invoice Reference Number (IRN), and returns a digitally signed QR code that you must print on the invoice.

The IRN authenticates the invoice's existence in the government's system. Buyers can verify any e-invoice by scanning the QR code, and the IRP automatically pushes the invoice data into the supplier's GSTR-1 and the buyer's GSTR-2B — eliminating data-entry errors and mismatches.

Current applicability threshold

e-Invoicing is mandatory for businesses whose aggregate annual turnover in any financial year from 2017-18 onwards exceeds the applicable threshold. The threshold has been progressively reduced:

As of 2026, the threshold stands at ₹5 crore. Any business that exceeded ₹5 crore aggregate turnover in any financial year from 2017-18 onwards must generate e-invoices for all applicable supplies.

Which documents require e-invoicing?

E-invoicing applies to the following document types for B2B supplies, exports and SEZ supplies:

• Tax invoices (regular B2B and export invoices)
• Credit notes
• Debit notes

B2C invoices (sales to unregistered individuals/consumers) do not require e-invoicing. However, for B2C supplies above ₹1 lakh (inter-state), a QR code must be printed on the invoice — but this is a different QR code (Dynamic QR Code for B2C), not the IRP-generated one.

Who is exempt from e-invoicing?

Even above the ₹5 crore threshold, the following categories are exempt from e-invoicing:

• Banking companies, financial institutions and NBFCs
• Insurance companies
• Goods Transport Agencies (GTAs) issuing consignment notes
• Passenger transport service providers
• Suppliers of services by way of admission to cinema/multiplex/exhibition
• Special Economic Zone (SEZ) units (as a supplier; SEZ developers are not exempt)
• Government departments for non-commercial purposes
• OIDAR (Online Information and Database Access or Retrieval) service providers

How the IRP and IRN work

The Invoice Registration Portal is operated by the NIC (National Informatics Centre) and private operators authorised by the GSTN. There are currently multiple IRPs available — the primary one is at einvoice1.gst.gov.in.

What is an IRN?

The IRN is a 64-character alphanumeric hash, computed as a SHA-256 hash of four fields: Supplier GSTIN, Financial Year (e.g., 2025-26), Document Type (INV, CRN, DBN) and Document Number (your invoice number). Because the hash depends on these four fields, the same invoice number can never produce a duplicate IRN — but any change to the invoice after IRN generation requires cancellation and re-generation (within the 24-hour window).

The QR code

The IRP returns a signed QR code containing: supplier GSTIN, buyer GSTIN, IRN, invoice number, invoice date, invoice value, number of line items, HSN of the main item and the digital signature. Anyone can verify the invoice by scanning the QR code with the government's official GST e-invoice verification app or any compatible QR scanner connected to the IRP.

End-to-end e-invoicing flow

1. Prepare the invoice — create the invoice in your billing software or ERP in the standard e-invoice JSON schema published by the GSTN. The schema requires supplier GSTIN, buyer GSTIN, HSN codes, GST rates, taxable values and tax amounts.
2. Upload to IRP — submit the JSON to the IRP via API (REST), bulk upload offline utility or through your billing software's e-invoicing integration.
3. IRP validation — the IRP validates that GSTINs are active, HSN codes are valid and the invoice data is complete. Invalid invoices are rejected with an error code.
4. IRN and signed QR returned — on successful validation, the IRP returns the 64-character IRN, a digitally signed invoice JSON and the QR code (Base64 encoded PNG or SVG). The IRP also sends the data to the GSTN for GSTR-1 auto-population.
5. Print on invoice — embed the IRN and the QR code image on your invoice PDF. The IRP requires the QR code to be physically printed (or displayed digitally) on every copy of the invoice.
6. Auto-population in GSTR-1 and GSTR-2B — within 24–48 hours, the e-invoice data appears in your GSTR-1 (you review and confirm) and in your buyer's GSTR-2B (they use it to claim ITC).

Cancellation and amendment

E-invoices can be cancelled on the IRP within 24 hours of IRN generation. After 24 hours, cancellation on the IRP is not possible — issue a credit note instead and report it via the amendment process in GSTR-1.

You cannot amend the content of an e-invoice after the IRN is generated. If a mistake is discovered after 24 hours, the standard GST procedure applies: issue a corrected invoice (new IRN) and a credit note against the original.

Penalties for non-compliance

Issuing an invoice without a valid IRN when e-invoicing is applicable is treated as issuing an invalid invoice. Consequences include:

• Penalty of ₹10,000 per invoice under Section 122 of the CGST Act for issuing an invoice in violation of the provisions.
• Penalty of 2% of the invoice value (up to ₹25,000) under Section 125 for general non-compliance.
• The buyer cannot claim ITC on the purchase — creating a financial disincentive that can affect business relationships.

How invoicing apps handle e-invoicing

Modern GST billing software integrates directly with the IRP via API, meaning the IRN generation is automatic — you raise an invoice in the app and the IRN and QR code are fetched and embedded before the PDF is generated. The buyer receives an invoice that already has the IRN and QR code printed on it.

BillRaja generates GST-compliant invoices with the correct CGST/SGST/IGST split and HSN codes — the foundation for e-invoice-ready JSON. Combined with the GST invoice generator, you have a complete invoicing workflow from bill creation to PDF sharing via WhatsApp.