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A small-business owner hears that e-invoicing is mandatory and does not know whether it means a different invoice, new software or both.
An e-invoice is a normal tax invoice uploaded to the IRP, which validates it and returns a 64-character IRN, acknowledgement number and signed QR code; the data then flows to GSTR-1 and the e-way bill system.
Check aggregate turnover against the ₹5 crore threshold, connect billing software to the IRP, print the IRN and QR code on every B2B invoice, and report within 30 days if turnover is ₹10 crore or more.
B2B invoices carry an IRN and QR code, GSTR-1 auto-fills from the IRP, and the buyer sees the same data in GSTR-2B.
An e-invoice is not a new kind of invoice. It is your normal GST tax invoice, but before you send it, its details are uploaded to the government’s Invoice Registration Portal (IRP). The IRP checks it and sends back a 64-character Invoice Reference Number (IRN) and a digitally signed QR code. You print both on the invoice. That is the whole difference.
Many people think “e-invoice” means a PDF sent by email. Under GST it means a registered invoice.
How does an e-invoice flow?
| Step | Who does it | What happens |
|---|---|---|
| 1. Create the invoice | Your billing software (Tally, Zoho, ERP) | Same fields as any tax invoice |
| 2. Upload to the IRP | Software or you, through the portal | Invoice data sent as a JSON file |
| 3. Validation | IRP | Checks GSTIN, duplicate number and format |
| 4. IRN and QR code returned | IRP | IRN, acknowledgement number and date, signed QR code |
| 5. Print and send | You | IRN and QR code shown on the invoice |
| 6. Data passed on | IRP to GST system | Auto-fills your GSTR-1 and, if details are given, Part A of the e-way bill |
Because the data reaches GSTR-1 directly, your buyer sees the same invoice in GSTR-2B. Fewer typing errors reach the return.
What does the IRN do for the buyer?
The IRN is proof that the invoice was registered. A buyer, or a tax officer at a checkpoint, can scan the QR code to confirm the supplier GSTIN, invoice number, date, value and the IRN without logging in anywhere. For a buyer claiming input tax credit, an e-invoice is far more likely to show up correctly in GSTR-2B than a hand-typed one.
Does a small business need e-invoices?
Only if its aggregate annual turnover crossed ₹5 crore in any financial year from 2017-18 onwards. That threshold has applied since 1 August 2023. Once you cross it, e-invoicing applies to all your B2B invoices, credit notes, debit notes and exports, even if turnover later falls.
Two more points:
- From 1 April 2025, businesses with turnover of ₹10 crore or more must register each invoice within 30 days of its date. After that the IRP refuses it.
- Sales to consumers (B2C) do not need an IRN.
Worked example: the same sale, two ways
A Bengaluru distributor sells goods worth ₹2,00,000 plus GST at 18 percent (₹36,000), a total of ₹2,36,000, to a registered retailer.
| Detail | Plain invoice (turnover ₹3 crore) | E-invoice (turnover ₹8 crore) |
|---|---|---|
| Invoice number and date | INV/26/0410, 7 October | INV/26/0410, 7 October |
| Taxable value and GST | ₹2,00,000 + ₹36,000 | ₹2,00,000 + ₹36,000 |
| IRN | None | 64-character code from the IRP |
| Acknowledgement number and date | None | Returned by the IRP, 7 October |
| QR code | Optional | Signed QR code printed |
| How it reaches GSTR-1 | Typed or uploaded by you before the 11th | Auto-filled from the IRP |
The commercial content is identical. Only the registration step and the three extra fields differ.
What to read next
- Next in this series: Can I cancel or correct an e-invoice after the IRN is generated?
- Matching books to IRP records: E-invoice IRN reconciliation in India
- Terms explained: GST reconciliation glossary
- GST reconciliation software: GST outward reconciliation (GSTR-1 and GSTR-3B) leads the TransactIG GST roadmap.