What Is an IRN in E-Invoicing?

What is an IRN in e-invoicing?

An IRN, or Invoice Reference Number, is a 64-character hash returned by the GST Invoice Registration Portal when an invoice is successfully reported under e-invoicing. It uniquely identifies that invoice, is generated from the supplier’s GSTIN, the document type, the document number and the financial year, and must be printed on the invoice along with the signed QR code the portal returns with it.

How the number is formed

The IRN is a hash computed from four things: the supplier’s GSTIN, the document type, the document number and the financial year. Because those four are unique to one document, the same invoice cannot be reported twice and a duplicate attempt is rejected by the portal rather than silently accepted.

What comes back with it

Alongside the IRN the portal returns an acknowledgement number and timestamp, a digitally signed QR code, and the signed invoice JSON. The IRN and the QR code both have to appear on the document you give the customer.

Why it matters

For invoices within the scope of e-invoicing, an unreported invoice is a compliance failure, and the reported invoice flows into GSTR-1 carrying its IRN. In practice the IRN is also the easiest way to prove a specific invoice was reported and when.

Is the IRN the same as the invoice number?

No. The invoice number is yours and you choose it; the IRN is a 64-character hash the portal computes and returns. Your invoice number is one of the inputs to it.

Can an IRN be cancelled?

Within the short cancellation window the portal allows, yes. After that the correct instrument is a credit note linked to the original invoice and its IRN.

What if the same invoice is reported twice?

It cannot be. Because the IRN is derived from the GSTIN, document type, number and year, a second attempt for the same document is rejected as a duplicate.