IRN in GST- Invoice Reference Number in India

IRN is an Invoice Reference Number. It is a unique number generated by the government's Invoice Registration Portal (IRP). The number used to tag and identify each valid e-invoice generated in India. The number firstly get implemented from 1st October 2020. This is a part of an e-invoicing system. It is used to make a standard for all e-invoices generated in India. This number maintains authenticity, prevents fraud and supports smooth compliance with tax regulations in GST.

What is an IRN (Invoice Reference Number)?

The IRN means an Invoice Reference Number. The Invoice Registration Portal (IRP) creates a unique 64-digit number. It is also called hash. This number uses a hash generation algorithm under the e-invoicing system. Every e-invoice generated in India get this number. So, the system gives this number for every document such as an invoice or debit or credit note. Each GSTIN (Goods and Services Tax Identification Number) must use a different number for each invoice it raises in a financial year in the entire GST system.

The tax officers use this number to check the authenticity of the transaction. They can check it through the central portal or the offline app. This helps them to check the invoice even if there is no internet.

Hash Generation Algorithm in IRN

A hash generation algorithm is a function in IRN that is used to convert a message or a string value. It contains a characters (alphabets + numbers + certain special characters) into a number ranges. As a result, it hides the original message. The GSTN (Goods and Services Tax Network) applies it as a part of the e-invoicing standard.

What is the Case Sensitivity IRN Generation GSTN Advisory?

The GST Network (GSTN) has issued an advisory. It is effective from 1st June 2025. The e-Invoicing system has treat IRN (Invoice Reference Numbers) as a case-insensitive. So, the Invoice Reporting Portal (IRP) treat invoice numbers as case-insensitive. This means, it is no longer matter if you use capital or small letters.

All invoice numbers will be changed to uppercase before generating IRN to keep things the same and avoid duplication. For example- "abc", "ABC", or "Abc". This change matches with the treatment of invoice numbers in GSTR-1.

The Parameters used to Generate IRN (Invoice Reference Number)

The Invoice Reference Number has been created by converting characters into numbers using a hash generation algorithm. This algorithm can be applied with three parameters. Here they are:

• Supplier GSTIN (Goods and Services Tax Identification Number)

• The document number of a Supplier. For example, invoice number

• The financial year in ‘YYYY-YY’ format. For example 2024-25.

What is the date of generating the Invoice Reference Number (IRN)?

The IRN (Invoice Reference Number) is generated at the time the seller issues an invoice, credit note, or debit note. This system is operational that applies to businesses across different turnover thresholds.

Below is the table that outlines the date and key changes:

The invoices under the e-invoicing system must prepare using a software. This helps business entity to generate invoices. Thus, they must follow the required standard and parameters.

The entity has two options to generate IRN (Invoice Reference Number). The options can include:

Option 1

You can use the Excel offline tool.

Option 2

You have the option to use API integration directly with the e-invoice portal/IRP. You can also use GST Suvidha Provider.

How to Generate an IRN?

The Government has given three different methods to businesses to generate IRN (Invoice Reference Number). Here are the methods:

Method 1: Generate IRN with Excel Utility Tool

Excel utility tool is applicable for companies with less number of invoices to process and simpler business hierarchy. It also helps small teams where they does not have a igh-end technical team in place.

Method 2: Generate IRN through API integration via E-invoice Portal

The government has implemented API (Application Programming Interface) to generate IRN. This suits companies with huge processing and a sound technical team. The technical must design the integration. They also manage the entire integration on their own. This DIY model can be cost-effective, it can lead to heavy fines in the long run. It caused due to the constant changes in the system, revisions in requirements, and stability issues.

Method 3: Generate IRN through GST Suvidha Provider (GSP) like IRIS GST

The government established the APIs for IRN Generation through GST Suvidha Provider (GSP). The GSPs are links between the government and taxpayers. This creates helpful and affordable platforms to assist taxpayer follow GST rules.

IRIS GST is a GSP that has an e-invoicing platform called IRIS Onyx. In this platform, users can connect their systems to the e-invoice portal and create IRN. The companies do not need much technical knowledge. They can perform huge tasks with little effort.

Conclusion

The IRN is an Invoice Reference Number. It is a unique identification number given to each invoice generated under the GST in India. This reduces the tax evasion, and gives transparency for business. The process makes the invoicing process simple for businesses. Thus, every business should know the e-invoicing system for business growth. If you have any queries related to it, get help from Online Legal India.

FAQ

Q1. What is IRN?

IRN means Invoice Reference Number—a unique 64-character alphanumeric code generated by the government’s Invoice Registration Portal for every valid e-invoice, including debit and credit notes.

Q2. Can I change or cancel an IRN after it is generated?

No. you cannot change or cancel an IRN (Invoice Reference Number) if it is generated.

Q3. Can I regenerate a new IRN for an invoice against which it was already generated?

No, you cannot regenerated a new IRN for an invoice against which it was already generated.

Q4. Is IRN Compulsory for All Types of Invoices?

No, the IRN (Invoice Reference Number) is not compulsory for all types of invoices.

Disclaimer

This article is for informational purposes only and does not constitute legal advice. Online Legal India is a digital platform. If you require legal assistance, we strongly recommend consulting a qualified lawyer or law firm.