GST E-Invoice Guide 2026 — Who Must Generate, Process, IRN, and Exemptions

E-invoicing under GST is mandatory for businesses above the turnover threshold. It ensures that every B2B invoice is registered on the government's Invoice Registration Portal (IRP) and gets a unique Invoice Reference Number (IRN). Here is the complete guide for 2026.

What is E-Invoicing?

E-invoicing is not a new type of invoice — it is the process of registering your existing B2B invoices on the government's IRP (Invoice Registration Portal) before sharing them with your buyer. The IRP validates the invoice and returns an IRN (Invoice Reference Number) and a QR code.

Key point: E-invoicing does not change the format of your invoice. It adds an IRN and QR code to your existing invoice.

Who Must Generate E-Invoices?

E-invoicing is mandatory for businesses with aggregate turnover above ₹5 crore in any preceding financial year.

Turnover threshold history:

• From October 2020: ₹500 crore
• From January 2021: ₹100 crore
• From April 2021: ₹50 crore
• From April 2022: ₹20 crore
• From October 2022: ₹10 crore
• From August 2023: ₹5 crore (current)

Which Transactions Require E-Invoicing?

E-invoicing is required for:

• B2B invoices (supply to registered persons)
• B2G invoices (supply to government)
• Exports (with or without payment of IGST)
• Credit notes and debit notes related to B2B transactions
• Reverse charge transactions (where buyer pays GST)

E-invoicing is NOT required for:

• B2C invoices (supply to unregistered persons)
• Nil-rated or exempt supplies
• Supplies by SEZ units
• Supplies by insurance companies, banks, NBFCs
• Supplies by GTA (Goods Transport Agency)
• Passenger transportation services

How to Generate an E-Invoice

Step 1: Prepare the Invoice

Create your invoice in your accounting software (Tally, Zoho, QuickBooks, etc.) with all mandatory fields:

• Supplier GSTIN, name, address
• Buyer GSTIN, name, address
• Invoice number and date
• HSN/SAC code
• Item description, quantity, unit price
• Taxable value, GST rate, CGST/SGST/IGST amounts
• Total invoice value

Step 2: Upload to IRP

Upload the invoice data to the IRP (Invoice Registration Portal) at einvoice1.gst.gov.in or through your accounting software's API integration.

The IRP validates:

• Supplier and buyer GSTINs
• Invoice number uniqueness
• Mandatory fields

Step 3: Receive IRN and QR Code

If validation is successful, the IRP returns:

• IRN (Invoice Reference Number): A unique 64-character hash
• Signed QR Code: Contains key invoice details
• Signed Invoice JSON: The complete invoice with digital signature

Step 4: Print and Share

Print the IRN and QR code on your invoice and share it with the buyer. The buyer can verify the invoice by scanning the QR code.

Auto-Population in GSTR-1

E-invoices are automatically populated in your GSTR-1. You do not need to manually enter B2B invoice details in GSTR-1 if you have generated e-invoices.

This is one of the biggest benefits of e-invoicing — it reduces manual data entry and errors in GSTR-1.

Cancellation of E-Invoice

An e-invoice can be cancelled within 24 hours of generation on the IRP. After 24 hours, you cannot cancel on the IRP — you must issue a credit note instead.

Important: Cancelling an e-invoice on the IRP does not automatically cancel it in GSTR-1. You must also cancel it in GSTR-1 or issue a credit note.

E-Way Bill Integration

If your e-invoice value exceeds ₹50,000 and involves movement of goods, an e-way bill is automatically generated along with the e-invoice. You do not need to generate a separate e-way bill.

Penalties for Non-Compliance

If you are required to generate e-invoices but do not:

• The invoice is treated as invalid under GST law
• The buyer cannot claim ITC on such invoices
• Penalty: ₹10,000 per invoice or 100% of tax, whichever is higher

GST 2.0 Changes (September 2025)

From September 22, 2025, GST 2.0 introduced changes that affect e-invoicing:

• New HSN codes for several product categories
• Updated validation rules on the IRP
• Integration with IMS (Invoice Management System) — buyers can accept/reject e-invoices

Frequently Asked Questions

Is e-invoicing required for B2C transactions?

No. E-invoicing is only for B2B, B2G, and export transactions. B2C invoices (to unregistered buyers) do not require e-invoicing.

What if the IRP is down when I need to generate an e-invoice?

The IRP has multiple portals (einvoice1 to einvoice6). If one is down, use another. In case of genuine technical failure, you have a grace period to generate the e-invoice.

Can I generate e-invoices for past dates?

No. E-invoices must be generated before or on the invoice date. You cannot generate an e-invoice for an invoice dated in the past.

Does e-invoicing apply to SEZ supplies?

No. Supplies by SEZ units are exempt from e-invoicing.

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