In India, taxpayers applicable under GST need to generate an e-way bill and an invoice for transporting goods worth more than ₹50000. Moreover, a person in charge of the conveyance of multiple consignments of goods has to provide several documents and invoices.

To ease this process of documentation, the Government of India introduced the concept of IRN (Invoice Reference Number) in the e-way bill system on 1 October 2020. Keep reading to learn more about Invoice Reference Numbers.

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IRN or Invoice Reference Number in GST is a 64-character alphanumeric number generated under the e-invoicing system of GST. To generate this number, a taxpayer has to upload their invoice on the Invoice Registration Portal (IRP). It is a unique number allotted to an invoice which enables tax authorities to verify the authenticity of transactions covered under the e-invoicing system.

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When generating Invoice Reference Number through the Invoice Registration Portal, it requires a hash generation algorithm. It is a mathematical function which converts any input comprising alphanumeric codes or characters into an output of unique numbers. This algorithm is an important standard of the e-invoicing system under GST. Application of this algorithm generates the IRN in an e-invoice according to certain parameters.

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Listed below are some parameters of the hash algorithm used for generating invoice reference numbers.

• GSTIN of a supplier/vendor.
• Document the number of a supplier such as an invoice or debit/credit note number.
• Format of the financial year.

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A supplier of the goods has to generate an invoice reference number at the time of issuance of an invoice or debit/credit note. The supplier can issue an invoice and generate IRN through the official GST portal. Additionally, there are several entities which provide GST portal services.