"e-Invoicing" sounds like it just means emailing a PDF. It does not. Under GST, e-invoicing is a specific process where every B2B invoice is reported to a government portal in real time and stamped with a unique number before you give it to the customer. If your business is above the threshold and you skip it, the invoice is not legally valid.
What Is an IRN?
When you report an invoice to the Invoice Registration Portal (IRP), it returns an IRN — Invoice Reference Number, a 64-character code unique to that bill, along with a signed QR code. Together they prove the invoice was registered with the government. Your printed invoice must show both.
The QR code lets anyone — a customer, a transporter, a tax officer — verify the invoice instantly by scanning it.
Who Must Generate e-Invoices?
e-Invoicing applies to businesses whose annual turnover has crossed ₹5 crore in any year since 2017-18, for their B2B supplies (sales to other GST-registered businesses) and exports. Sales to end consumers (B2C) are excluded. A separate rule asks only very large businesses, with turnover above ₹500 crore, to print a dynamic payment QR code on B2C invoices.
e-Invoicing started at ₹500 crore in October 2020 and was lowered in stages to ₹5 crore from 1 August 2023, where it still stands. If your turnover is growing, check it every year: the test is whether you crossed ₹5 crore in any year since 2017-18.
How the Process Actually Works
- You create the invoice in your billing software as usual
- The software sends the invoice data to the IRP (the NIC e-invoice portal)
- The IRP validates it and returns the IRN + signed QR code in a second or two
- Your invoice — now carrying the IRN and QR — is printed or shared with the customer
- The data flows automatically into your GSTR-1, so you do not enter it twice
Watch the 30-day limit. If your turnover is ₹10 crore or more, the IRP rejects an invoice, credit note or debit note reported more than 30 days after its date (applies since 1 April 2025). Generate the IRN on the day you bill.
Do You Need a Heavy ERP?
No. This is the biggest myth. You do not need Tally with a GSP subscription or an expensive ERP. Any modern billing tool with a built-in IRP connection can generate an IRN at the click of a button.
Billux connects directly to the NIC e-invoice system: you enter your IRP credentials once, and after that the "Generate IRN" button on any invoice fetches the IRN and QR and prints them on the bill — with a sandbox mode so you can test before going live.
Penalties for Getting It Wrong
An invoice that should have an IRN but does not is treated as no invoice at all. The penalty is generally ₹10,000 or the tax due, whichever is higher, per invoice, and your customer cannot claim input credit on it — which makes B2B buyers refuse non-compliant bills quickly.
The Bottom Line
If you are near ₹5 crore, e-invoicing is not optional and not hard — it is a one-time setup plus a button. Get software that talks to the IRP for you.
Start free at billux.in/register.
Frequently Asked Questions
What is an IRN in e-invoicing?
IRN stands for Invoice Reference Number, a 64-character unique code the Invoice Registration Portal returns when you report an invoice. It comes with a signed QR code, and both must appear on the invoice you give the buyer.
Is e-invoicing mandatory below ₹5 crore turnover?
No. e-Invoicing applies only if your aggregate turnover crossed ₹5 crore in any financial year since 2017-18. Below that, a normal GST tax invoice is valid. Check your turnover every year, because crossing the limit once makes e-invoicing compulsory from then on.
What is the 30-day limit for e-invoices?
Since 1 April 2025, businesses with turnover of ₹10 crore or more cannot report an invoice, credit note or debit note to the IRP more than 30 days after its date. The portal rejects late reports.
Do I need e-invoices for B2C sales?
No. e-Invoicing covers B2B supplies and exports. Separately, only businesses with turnover above ₹500 crore must print a dynamic payment QR code on B2C invoices. A shop selling to walk-in consumers does not need an IRN for those bills.
What is the penalty for not generating an e-invoice?
An invoice that should have had an IRN is not treated as a valid invoice. The penalty is generally ₹10,000 or the tax due, whichever is higher, per invoice, and the buyer cannot claim input tax credit on it.
