E-Invoice – Invoice Reference Number

The Invoice Reference Number (IRN) is a 64-digit along alphanumeric number to
uniquely identify each B2B Invoice issued in India. The IRN is calculated
from the following details:

• Supplier GSTIN
• Financial Year of the Invoice
• Document Type (Invoice, Credit Note, etc.)
• Invoice Number or Document Number

by concatenating the details together and computing a SHA 256
hash.

Details of an Invoice Reference Number (IRN)

For example, the IRN for the following invoice details

• Supplier GSTIN - 29AAFCC9980M1ZR
• Financial Year - 2019-20
• Document Type - Invoice
• Invoice Number - 2019-20/KA/1

will be SHA265("29AAFCC9980M1ZR2019-20INV2019-20/KA/1") which is
23f498ee41441ecad30f72ba5b9907506c3df70a17b0e0dff46b76a786400662.

How to generate Invoice Reference Number?

Any supplier using their accounting software can generate an IRN against
each invoice. In fact a user could print a bill book (though that would go
against the whole concept of e-Invoice) of serially running invoices with
unique IRNs. However, the Invoice and IRN alone are not valid.

Who needs to generate E-Invoice?

As per CGST Rule 48(4) - Manner of Issuing Invoice and
CGST Notification 70/2019, tax payers with aggregate
turnover in a financial year more than Rs. 100 Crore are required to
generate an e-Invoice, register it with a Government-approved Invoice
Registration Portal (IRP), receive an Invoice Reference Number
(IRN).

Validation of E-Invoice

To help a recipient or buyer validate that their supplier has registered
their invoice with the Invoice Registration Portal (IRP), the
IRP will issue a digitally signed invoice and Quick Response Code (QR
Code). The supplier can print the QR Code on their invoice or directly
share the digitally signed invoice with their customer.