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E-Invoice

E-invoicing under GST: the complete implementation guide for India

March 20, 2026
4 min read

E-invoicing is no longer optional for large businesses in India. If your aggregate annual turnover exceeds ₹5 crore, you must register every B2B invoice with the government's Invoice Registration Portal (IRP).

But e-invoicing is more than just adding a QR code to your invoice. It changes how you generate invoices, how your buyers claim ITC, and how the government monitors tax compliance.

This guide explains everything you need to know about e-invoicing in India.

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Who must comply with e-invoicing in India?

  • Current threshold: Businesses with aggregate annual turnover exceeding ₹5 crore in any financial year from FY 2017-18 onwards must implement e-invoicing.
  • What counts as turnover: Aggregate turnover includes all taxable supplies, exempt supplies, exports, and inter-state supplies across all GSTINs under the same PAN.
  • B2B invoices only: E-invoicing is mandatory only for supplies to registered businesses (B2B).
  • Special categories: Government departments, SEZ units, and insurance/banking companies have specific exemptions.
  • Voluntary adoption: Businesses below the threshold can voluntarily adopt e-invoicing.

How e-invoicing works — the step-by-step process

  • Step 1: Generate invoice in your billing software: Create the invoice as usual with all mandatory GST fields.
  • Step 2: Convert to JSON format: Your billing software converts the invoice data into the standardized JSON schema.
  • Step 3: Upload to IRP via GSP: The JSON is uploaded to the Invoice Registration Portal through a GST Suvidha Provider.
  • Step 4: IRP validation and registration: The IRP validates the invoice data. If valid, it generates an Invoice Reference Number (IRN) — a unique 64-character hash.
  • Step 5: IRP adds QR code and digital signature: The IRP embeds a digitally signed QR code containing key invoice details.
  • Step 6: Download and share e-invoice: The registered invoice (with IRN and QR code) is returned to you.
  • Step 7: Auto-population in GSTR-1: The e-invoice data automatically flows into your GSTR-1 and your buyer's GSTR-2B.

What changes on your invoice with e-invoicing

  • New fields added: IRN (64-character unique identifier), Acknowledgment Number, Acknowledgment Date, and QR Code.
  • QR Code content: The QR code contains GSTIN of supplier and recipient, invoice number, date, total value, tax amount, and HSN code summary.
  • No signature required: For e-invoices, the IRP's digital signature on the QR code serves as authentication.
  • 8-digit HSN mandatory: For e-invoicing businesses, 8-digit HSN codes are required for goods.
  • Format flexibility: You can design your invoice PDF as you like, as long as the IRN and QR code are clearly visible.

E-invoicing implementation — technical options

  • Option 1: Billing software with built-in e-invoicing: Modern billing software has direct IRP integration. You create invoices normally; e-invoicing happens in the background.
  • Option 2: GSP integration: If your current software doesn't support e-invoicing, integrate with a GST Suvidha Provider.
  • Option 3: Excel-to-IRP utility: For low volumes, use the free IRP Excel utility.
  • Option 4: API integration: Large enterprises with custom ERPs can integrate directly with IRP APIs.
  • Offline mode: The IRP supports offline generation for businesses with intermittent internet.

Common e-invoicing mistakes and how to avoid them

  • Mistake 1: Sending invoice before IRN generation: An invoice without IRN is not a valid e-invoice.
  • Mistake 2: Duplicate invoice numbers: The IRP rejects invoices with duplicate numbers within the same financial year.
  • Mistake 3: Incorrect HSN codes: The IRP validates HSN codes against the master database.
  • Mistake 4: GSTIN mismatches: If the buyer's GSTIN is wrong, the invoice is rejected.
  • Mistake 5: Not canceling e-invoices properly: If you need to cancel an e-invoice, do it within 24 hours on the IRP.

Benefits of e-invoicing beyond compliance

  • Auto-populated returns: Your GSTR-1 is auto-populated from e-invoice data.
  • Faster ITC for buyers: Your buyer's GSTR-2B is updated in real-time.
  • Reduced tax evasion: The government can track invoices in real-time.
  • Standardized data: E-invoicing uses a standardized schema, making integration easier.
  • E-way bill integration: For goods movement, e-invoice data can auto-generate e-way bills.

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