E-Invoicing in India: A Complete Guide to the GST E-Invoice System

What Is E-Invoicing in India?

E-invoicing (electronic invoicing) under GST is a system where B2B invoices are electronically authenticated by the government before being issued. It does not mean generating invoices on a computer — it refers to a specific validation process through the Invoice Registration Portal (IRP).

Here is how it works:

1. You create an invoice in your accounting or billing software as usual
2. Your software sends the invoice data to the IRP in a standardised JSON format
3. The IRP validates the data, checks for duplicates, and assigns a unique Invoice Reference Number (IRN)
4. The IRP also generates a QR code and a digitally signed e-invoice
5. The validated invoice data is automatically shared with the GST portal and the e-way bill system

The key point: e-invoicing adds a verification layer to your existing invoicing process. It does not replace your accounting software or change the content of your invoices.

Who Needs to Generate E-Invoices?

E-invoicing is mandatory based on your aggregate turnover in any financial year from 2017-18 onwards:

Exemptions

The following categories are exempt from e-invoicing even if they meet the turnover threshold:

• Special Economic Zone (SEZ) units
• Insurance companies
• Banking and financial institutions
• NBFCs
• Government departments
• Local authorities
• Persons registered under Section 10 (composition scheme)

The E-Invoice Process Step by Step

Step 1: Generate the Invoice

Create the invoice in your ERP, accounting software, or billing tool. The invoice must include all mandatory GST fields — supplier and recipient GSTIN, HSN/SAC codes, tax breakdown, and so on.

Step 2: Convert to JSON Format

Your software converts the invoice data into the e-invoice schema — a standardised JSON format defined by GSTN. This includes the document details, seller and buyer information, item details, and tax values.

Step 3: Push to the IRP

The JSON payload is sent to the IRP via API. The IRP validates the data against the GST database:

• Checks that both GSTINs are active
• Verifies that the invoice number is unique for the financial year
• Validates the HSN/SAC codes and tax calculations

Step 4: Receive the IRN and QR Code

If validation passes, the IRP returns:

• IRN (Invoice Reference Number) — a unique 64-character hash generated from the supplier GSTIN, financial year, document type, and document number
• QR code — contains key invoice details for quick verification
• Digitally signed invoice — the JSON payload with the IRP's digital signature

Step 5: Print or Share the Invoice

Add the IRN and QR code to your invoice PDF before sharing it with the buyer. The QR code allows anyone to verify the invoice using the GST Verification app.

Common E-Invoicing Errors

E-Invoicing and E-Way Bills

One major benefit of e-invoicing is automatic e-way bill generation. When you generate an e-invoice for goods transport, the system can auto-populate Part A of the e-way bill using the e-invoice data. You only need to fill in Part B (transporter details and vehicle number).

This eliminates the need to enter the same data twice and reduces errors.

Impact on Input Tax Credit (ITC)

E-invoicing directly affects ITC claims. The buyer's GSTR-2A and GSTR-2B are auto-populated from e-invoices, which means:

• The buyer can verify ITC eligibility in real time
• Mismatches between supplier and buyer records are caught earlier
• Invoices not registered on the IRP cannot be used for ITC claims (when e-invoicing is mandatory for the supplier)

Create a GST-Compliant Invoice

Our India invoice generator includes all mandatory GST fields. While it does not connect to the IRP directly, it produces invoices with the correct structure and tax calculations that you can then push through your e-invoicing software.