E-invoicing under GST is widely misunderstood. It doesn’t mean you generate your invoices on a government website. It means you generate them in your own system as normal, then register each B2B invoice on a government portal called the IRP (Invoice Registration Portal), which assigns a unique reference number and QR code. That registration is what makes the invoice “electronic” in the GST sense.
If your business crosses the turnover threshold and you’re issuing B2B invoices without this, your buyers cannot legally claim ITC on them.
Who must e-invoice under GST
E-invoicing is mandatory for registered taxpayers whose aggregate annual turnover exceeds ₹5 crore in any preceding financial year. The threshold has been progressively lowered since the system launched:
| Effective date | Turnover threshold |
|---|---|
| October 2020 | ₹500 crore |
| January 2021 | ₹100 crore |
| April 2021 | ₹50 crore |
| April 2022 | ₹20 crore |
| October 2022 | ₹10 crore |
| August 2023 | ₹5 crore |
If your turnover crossed ₹5 crore in FY 2024-25, e-invoicing is mandatory for you from the start of FY 2025-26, even if turnover drops below the threshold in the current year.
Who is exempt even above the threshold: Insurers, banks, financial institutions, NBFCs, GTA (goods transport agencies), passenger transport services, and SEZ units are exempt. So are B2C transactions (you only need to e-invoice for B2B, B2G, and exports — not for sales to end consumers).
How to generate a GST e-invoice: the actual process
Step 1 — Prepare the invoice in your software. Use your accounting software, ERP, or billing tool as usual. The invoice data must be in the GST e-invoice schema format (JSON), but most accounting software handles this automatically.
Step 2 — Upload to the IRP. Send the invoice JSON to the Invoice Registration Portal via API (automated, for businesses with ERP integration) or through the government’s web portal at einvoice1.gst.gov.in.
Step 3 — IRP validates and returns IRN + QR code. The IRP checks for duplicate invoice numbers, validates the GSTINs, and if everything is correct, returns an IRN (64-character hash) and a signed QR code within seconds.
Step 4 — Print IRN and QR code on the invoice. Every copy of the invoice you send to the buyer must carry the IRN and QR code. The buyer scans the QR to verify the invoice is genuine.
Step 5 — IRP auto-populates GSTR-1. The validated invoice data automatically flows into your GSTR-1 return for that period. You don’t have to enter it again.
What the IRN is and how it works
The IRN is a 64-character alphanumeric unique identifier generated by the IRP using a hash of four fields: your GSTIN, the financial year, the document type (INV/CRN/DBN for invoice/credit note/debit note), and your invoice number.
This means:
- Two invoices with the same number from the same taxpayer in the same year generate the same IRN — duplicates are automatically rejected
- The IRN is permanent — once issued, it can’t be changed. If you cancel an invoice, you cancel the IRN within 24 hours and issue a new invoice
Cancellation window: 24 hours
If you made a mistake on an e-invoice, you have 24 hours from the time the IRP issued the IRN to cancel it. After 24 hours, the IRN cannot be cancelled through the IRP. You’d need to issue a credit note against the original invoice instead.
This is a significant operational constraint. Many businesses that issue large volumes of invoices have discovered this the hard way — an error noticed 25 hours after generation becomes a credit-note problem, not a simple cancellation.
Penalty for not e-invoicing when required
The penalty is ₹10,000 per invoice under Section 122 of the CGST Act for issuing an invoice in violation of the provisions. More practically, if a buyer’s GSTR-2B doesn’t show your invoice (because it was never uploaded to the IRP), they can’t claim ITC on it — and an unhappy buyer who lost ITC is a more immediate business consequence than the statutory penalty.
This generator for non-e-invoice businesses
The invoice generator on this page produces a standard GST invoice. If your turnover is below ₹5 crore, this is all you need — no IRP registration required. For businesses above the threshold, use this to understand the invoice structure; your actual e-invoice generation should happen through your accounting software or the IRP directly.
Related: GST invoice template for the standard tax invoice format, and the GST calculator for working out CGST/SGST/IGST amounts.