IRN and the QR code on your invoice, explained

The IRN is the unique number the Invoice Registration Portal gives your invoice; the signed QR code is its proof. What to print, and how to fix a wrong one.

The IRN, or Invoice Reference Number, is the unique number the Invoice Registration Portal (IRP) gives your invoice when you report it. The signed QR code is the portal's digitally signed proof of that registration. If e-invoicing applies to you, the signed QR code, which carries the IRN, goes on the invoice you hand to the buyer, and most businesses also print the IRN beside it. Neither can be edited once issued.

Last reviewed: October 2026. Who must generate e-invoices, the time allowed to cancel an IRN and other portal rules are set by GST notifications and the portal, and they change. Confirm the current position on the official e-invoice portal or with your CA.

What is an IRN?

An IRN is a long reference string that the IRP creates for one invoice. You do not type it in. You send the invoice details to the portal, the portal checks them, and it returns the IRN with a signed copy of the invoice and a signed QR code.

Whether you need an IRN at all depends on your turnover and your type of business. That question is covered in do you need to generate e-invoices? This post assumes you already do.

An e-invoice is still your normal tax invoice. The IRN and QR code are added to it. The rules on what the invoice itself must show are in what a GST invoice must contain.

How is the IRN created, and why does my invoice number matter?

The portal builds the IRN from four things: your GSTIN, the document type (invoice, credit note or debit note), the document number and the financial year of the document date. The same four details always give the same IRN.

That has one practical effect. The portal will not register the same document number twice in a financial year for the same document type. If your billing repeats a number, perhaps because two counters share one series, the second invoice is rejected.

So keep one clean number series for each document type and each financial year. The portal also says that an IRN cannot be generated again for a cancelled invoice, so a cancelled number cannot be reused.

What does the signed QR code show?

The QR code carries the IRN and the key details of the invoice, such as the supplier and buyer GSTINs, the invoice number, date and value. The portal signs this data digitally, so any change to it can be detected.

The signature is what matters. A QR code that you draw yourself from your own billing data is not the signed QR code. Print the one the portal returns.

What exactly must I print on the invoice?

Print the invoice as usual, plus the IRN and the signed QR code the portal returned. Check three things before the first e-invoice leaves your shop:

The IRN is complete. It is long, and a narrow print layout can cut it off.
The QR code scans. Print a test copy and scan it with the official verify app. A code that is too small or blurred is a problem at the buyer's end.
The print matches what was reported. If someone edits the invoice in your billing after registering it, the paper and the portal no longer agree.

Ask your CA whether your printed copy still needs a manual signature.

How does a buyer check that an e-invoice is genuine?

The official e-invoice portal provides a verify QR code app and a verify signed invoice option. A buyer can scan the QR code, see the details the portal holds, and compare them with the bill in hand.

If you buy from a supplier who issues e-invoices, it is worth checking a few when you receive goods. A mismatch between the QR code and the bill is easier to fix that day than at GSTR-2B reconciliation time.

What if the e-invoice is wrong?

You cannot edit an invoice on the portal once it has an IRN. You have two routes, depending on how quickly you notice:

When you notice	What you can do
Within the cancellation window the portal allows	Cancel the IRN on the portal, then raise a fresh invoice with a new number
After the window has closed	Correct it through the return process, usually with a credit note or debit note, as your CA advises

Two limits apply to cancellation. An IRN cannot be cancelled while a valid e-way bill is active for it, so cancel the e-way bill first if the goods have not moved. And a cancellation covers the whole invoice; you cannot change part of it.

The cancellation window is short. Treat a wrong e-invoice as same-day work.

Does the IRN change what I report in my returns?

No. You still report the invoice in GSTR-1. The details of a registered e-invoice can flow into your return, which reduces re-keying, but you remain responsible for checking and filing it. See filing GSTR-1 straight from your sales records.

FAQ

What is an IRN in an e-invoice? IRN stands for Invoice Reference Number. It is the unique number the Invoice Registration Portal returns when you report an invoice to it. The portal builds it from your GSTIN, the document type, the document number and the financial year, so each invoice number can be registered only once in a financial year.

Can I edit an e-invoice after the IRN is generated? No. The portal does not let you change a registered invoice. If the invoice is wrong, you can cancel the IRN within the short window the portal allows, provided no active e-way bill is linked to it, and then raise a fresh invoice. After that window, ask your CA how to correct it, usually through a credit or debit note.

How can my buyer check that an e-invoice is genuine? The QR code on an e-invoice is digitally signed by the Invoice Registration Portal. The official e-invoice portal offers a verify QR code app and a verify signed invoice option. Your buyer can scan the code with these to confirm that the portal registered the invoice and that the key details match the bill in hand.

If you would rather your billing kept the invoice details your returns are built on in one place, see what KillStock does out of the box.