GST glossary
IRN
Invoice Reference Number
An IRN is the unique 64-character reference the Invoice Registration Portal gives an e-invoice when it accepts it. An e-invoice without an IRN is not a valid invoice, and your customer cannot claim input tax credit on it.
Why it matters to your business
The IRN is the proof that your invoice has been registered with the GST system. Your customer’s accountant will look for it before booking your bill, and tax officers checking a vehicle can scan the QR code to confirm the invoice is genuine. If an invoice that should have an IRN does not, your customer loses credit and you may be asked to issue it again.
How it works
As of September 2026:
- The invoice is reported to an Invoice Registration Portal, by your software or as a file you upload on the portal.
- The IRP checks it and creates the IRN, a 64-character code unique to your GSTIN, the year, the document type and the number.
- It returns the IRN, an acknowledgement number and date, and a QR code signed by the IRP.
- You print the IRN and QR code on the invoice. For businesses with turnover of ₹10 crore or more, this must happen within 30 days of the invoice date.
What you can and cannot change
- Cancel: within 24 hours, in full. The cancelled number cannot be reused.
- Amend: the IRP does not amend. Changes are made through a credit or debit note, or by amending the invoice in your GSTR-1 where the law allows.
- Duplicate: sending the same number twice is refused as a duplicate, and the IRP points you to the IRN already issued.
Common mistakes
- Sharing an invoice PDF with the customer before the IRN is on it.
- Cancelling a correct invoice to change a small detail, and then being unable to reuse the number.
- Treating a failed IRN as done. Check that every covered invoice has an IRN before month end.
Questions about IRN
How is an IRN generated?
The Invoice Registration Portal generates it from the supplier's GSTIN, the financial year, the document type and the document number, using a hashing method. That is why the same invoice number cannot get two IRNs in one year.
Can I cancel an IRN?
Yes, within 24 hours of generating it, and only for the whole invoice. After 24 hours, correct the sale with a credit note. The number of a cancelled invoice cannot be used again for a new IRN.
What is in the QR code printed with the IRN?
The supplier's and customer's GSTINs, the invoice number and date, the invoice value, the number of lines, the HSN code of the main item, and the IRN with its date, all digitally signed by the IRP.
Does every invoice need an IRN?
Only invoices covered by e-invoicing, that is business-to-business invoices, exports and SEZ supplies of a business whose turnover has crossed ₹5 crore. Sales to consumers do not need one.
Updated .