E-invoicing under GST is a system where businesses above the notified turnover limit (currently ₹5 crore aggregate turnover) report each B2B invoice, export invoice, credit note and debit note to a government Invoice Registration Portal (IRP). The IRP validates it, assigns a unique Invoice Reference Number (IRN), digitally signs it and returns a QR code. Without an IRN, such an invoice is not valid.
E-invoicing is one of those GST terms that sounds like "sending invoices by email", but it means something much more specific. Under GST, an e-invoice is an invoice whose data has been reported to a government portal, checked, stamped with a unique number and returned with a signed QR code. This guide explains what that process is, why it exists, who it applies to and what changes in your day-to-day billing.
What does e-invoicing mean under GST?
Under Rule 48(4) of the CGST Rules, 2017, the government can notify a class of registered persons who must prepare their invoices in a prescribed electronic format and upload the details to a common portal. That uploaded invoice is what the law calls an e-invoice. The portal that receives it is the Invoice Registration Portal (IRP).
The key point is that you still create the invoice in your own system — your billing software, ERP or accounting package. E-invoicing does not mean the government writes your invoice for you. What changes is that, before the invoice is treated as validly issued, its data must be registered with the IRP.
When the IRP accepts your invoice, it returns three things:
- An Invoice Reference Number (IRN) — a unique 64-character hash that identifies that document.
- A digital signature of the IRP on the invoice data.
- A signed QR code that contains the key details of the invoice and can be verified offline.
You then print or share the invoice with the IRN and QR code on it. Rule 48(5) says that an invoice issued by a notified person without following this process is not treated as an invoice at all. That is why e-invoicing is not optional paperwork for covered businesses: it decides whether your buyer can claim input tax credit.
Why did India introduce e-invoicing?
E-invoicing was rolled out from 1 October 2020 for the largest taxpayers and extended in stages to smaller ones. The government's stated aims are practical:
- One-time data entry. The same invoice data feeds GSTR-1 and, where needed, the e-way bill, so businesses type it once instead of three times.
- Real-time visibility. Because invoices are registered as they are issued, the tax system sees B2B supplies almost immediately rather than at month-end.
- Fewer fake invoices. A signed IRN and QR code make it much harder to create paper invoices for supplies that never happened and pass on bogus input tax credit.
- Standard format. All covered businesses report in the same schema, so buyers' and sellers' systems can read each other's data.
For a business owner, the biggest everyday benefit is the auto-filling of GSTR-1 and the e-way bill from data you already entered once.
Who has to issue e-invoices?
The mandate is turnover-based. It applies to a registered person whose aggregate turnover in any financial year from 2017-18 onwards has exceeded ₹5 crore. That threshold was set by Notification 10/2023-Central Tax and has applied from 1 August 2023. The limit has come down in steps from ₹500 crore at launch, so it is worth checking it every year.
The rules on the exact calculation, the "any preceding year" test, and what happens when turnover dips later are explained in our guide to the e-invoice applicability limit. Some classes of business — such as SEZ units, banks and insurers, goods transport agencies and government departments — are excluded even above the limit; see e-invoice exemptions for the list.
Which documents and transactions are covered?
E-invoicing covers business-to-business (B2B) documents and certain related supplies. The table below gives a quick reference.
| Document / supply | IRN needed? | Notes |
|---|---|---|
| Tax invoice to a registered buyer (B2B) | Yes | The core use case |
| Supply to an SEZ unit or developer | Yes | With or without payment of tax |
| Export of goods or services | Yes | With or without payment of IGST |
| Deemed exports | Yes | Reported with the relevant supply type |
| Credit note / debit note on the above | Yes | Must be reported like the invoice |
| Invoice to an unregistered consumer (B2C) | No | Separate dynamic QR rules may apply to large sellers |
| Delivery challan | No | Not a tax invoice |
| Bill of supply | No | Not covered |
| Imports (bill of entry) | No | Not an outward supply |
If you are unsure whether a document should be a tax invoice or a bill of supply in the first place, the guide on tax invoice vs bill of supply is the right starting point.
How does the e-invoicing process work, step by step?
The flow is the same whether you use the government's free tools or a billing system connected through APIs.
- Create the invoice in your system. Enter buyer GSTIN, items, HSN codes, quantities, values and tax as usual.
- Generate the JSON. Your software converts the invoice into the standard e-invoice JSON format (schema INV-01). The structure is explained in e-invoice JSON schema.
- Upload to an IRP. The JSON goes to the IRP through the portal's bulk upload tool, the offline utility, or an API connection.
- Validation. The IRP checks the GSTINs, the format, HSN codes, totals, and that the same document number has not already been registered by you in that financial year.
- IRN and QR returned. If everything passes, the IRP generates the IRN, signs the data and returns it with the QR code.
- Share with the buyer. You print or email the invoice with the IRN and QR code.
- Data flows onward. The IRP sends the data to the GST system for GSTR-1 auto-population and, if you supplied transport details, to the e-way bill system.
A detailed walk-through of the portal screens is in how to generate IRN.
A worked example: what changes on one invoice
Suppose a Pune hardware distributor with ₹7.2 crore turnover last year sells fittings to a registered contractor in Nashik.
| Line | Amount |
|---|---|
| 400 brass valves at ₹350 | ₹1,40,000 |
| 200 pipe couplers at ₹90 | ₹18,000 |
| Taxable value | ₹1,58,000 |
| CGST 9% | ₹14,220 |
| SGST 9% | ₹14,220 |
| Invoice total | ₹1,86,440 |
Both parties are in Maharashtra, so CGST and SGST apply at 9% each (18% total). Because the distributor's turnover exceeded ₹5 crore in a previous financial year, the invoice must be reported to the IRP.
Without e-invoicing, the distributor would issue the invoice, type the same details later into GSTR-1, and separately enter them on the e-way bill portal (the consignment value is above ₹50,000).
With e-invoicing, the billing software sends the invoice JSON with transporter details to the IRP. Within seconds it receives the IRN, signed QR code and, if Part B was included, an e-way bill number. The invoice is printed with the QR code. At month-end, the invoice already appears in the distributor's GSTR-1 draft. The buyer sees it in their GSTR-2B through the normal flow once GSTR-1 is filed.
Same invoice, same amounts, but one data entry instead of three.
What does e-invoicing change in daily operations?
For most businesses the changes fall into four areas.
Invoice numbering
The IRP rejects a second IRN request for the same supplier GSTIN, document type, document number and financial year. You cannot reuse a number even after cancelling the IRN. Keep a clean, sequential series; see GST invoice number series rules.
Master data quality
Buyer GSTINs, state codes, PIN codes and HSN codes must be correct, because the IRP validates them. A wrong PIN code for the buyer's state is one of the most common rejection reasons.
Timing
Businesses with aggregate annual turnover of ₹10 crore or more cannot report an invoice to the IRP more than 30 days after its document date; this restriction has applied since 1 April 2025 under a GSTN advisory. The detail is in the 30-day reporting limit.
Corrections
An IRN can be cancelled only in full and only within 24 hours of generation. After that, corrections go through credit or debit notes. See how to cancel an e-invoice.
What are the ways to generate e-invoices?
You can choose a method according to volume.
| Method | Best for | How it works |
|---|---|---|
| Portal / offline utility | A few invoices a month | Prepare JSON with the offline tool and upload, or enter on the portal |
| GSP / software integration | Regular B2B billing | Billing software calls the IRP API through a GST Suvidha Provider |
| Direct API | Large volumes | Your ERP connects to the IRP with your own API credentials |
Billing Software by Betterwork, for example, generates the IRN and e-way bill from the invoice screen itself, so the QR code prints on the first copy without any manual JSON upload. Whichever method you pick, the legal result is the same IRN and QR code.
Common mistakes with e-invoicing
- Assuming the email PDF is enough. Covered businesses need an IRN; a PDF without one is not a valid tax invoice for them.
- Ignoring old-year turnover. The test looks at any financial year since 2017-18, not just last year.
- Issuing B2B invoices first and "registering later". For businesses with turnover of ₹10 crore or more, invoices older than 30 days will be refused.
- Reusing a cancelled number. The IRP treats it as a duplicate.
- Leaving e-way bill and e-invoice details out of sync. Cancel the e-way bill before you cancel the IRN.
- Treating credit notes as optional. They need IRNs too when the original invoice did.
Key takeaways
- E-invoicing means registering B2B invoice data with an IRP and receiving an IRN and signed QR code.
- It is mandatory once aggregate turnover in any year since 2017-18 crossed ₹5 crore, subject to listed exemptions.
- Without the IRN, a covered business's invoice is not a valid invoice, which can block the buyer's input tax credit.
- The same data auto-fills GSTR-1 and can generate the e-way bill.
- Respect the 24-hour cancellation window and, at ₹10 crore and above, the 30-day reporting limit.
If you want to see the process on your own invoices, you can book a demo or browse the features page.
This guide is general information, not tax advice. Rules last checked on 20 October 2026; confirm with your tax professional for your situation.