What is Invoice Reference Number (IRN) in GST? Format and How to Generate IRN?


Yarab A, Jan-15-2020

With the concept of e-Invoicing, which is proposed to be implemented from 1st April 2020 (trial mode from 1st January,2020), an invoice is valid only if the “IRN’ is mentioned in the invoice. Invoice being an important document in business, it is of utmost necessary to understand the fundamentals of IRN and the change that may be required in the way the invoices are issued.

In this article, we’ll discuss everything about IRN right from its meaning, format and how to generate it.

What is IRN?

IRN known as “Invoice Reference Number” is a unique invoice number generated by the Invoice Register Portal (IRP) on uploading the invoice electronically.

Under the e-invoicing system in GST, documents such as Invoice, Credit Note, Debit Note or any such document as required by the law should be electronically uploaded to IRP system. Every time a unique document is uploaded in the prescribed format, a unique reference number know as Invoice Reference Number (IRN) is generated by the system.

IRN is also referred to as ‘Hash’ in technical terms.

Parameters and Format of IRN

The IRN is computed considering the GSTIN of a generator of the document (invoice or credit note etc.), document number like invoice number and the financial year.

  • Supplier GSTIN,
  • Supplier’s invoice number
  • Financial year (YYYY-YY)

How to Generate IRN for e-invoice?

The responsibility of generating e-invoice with IRN is with the creator of the document. Let’s say, the responsibility of uploading tax Invoice is with the supplier of goods or services. The IRP system, a portal designed to authenticate invoices, will accept invoices only in JSON format in a specified structure.  

To generate e-invoice IRN, there are two possible options available for business.

Option -1

Here, the businesses are expected to generate the e-invoice in the JSON format using their accounting software and upload it to the IRP system. You can also generate e-invoice JSON using any software utility that generates invoice including those using excel or GSTN provided offline utility.

The IRP system will validate the invoice data and generates the IRN for the document uploaded. Along with the IRN, a digitally signed invoice with QR code is sent to the supplier as well as the buyer. 


The interesting feature of IRN under e-invoice concept is about generating IRN using accounting or billing software by applying the provided algorithm. In this scenario, e-invoice JSON generated along with IRN using accounting software is uploaded to the IRP system. The IRP system validates the IRN generated by the software and accordingly sends the digitally signed invoice with QR Code.

This option allows businesses to pre-generate and print IRN on the invoice and then upload the invoice to the IRP system. Remember, an invoice remains valid only if it has IRN and is uploaded to the IRP system.