How to Generate E-Invoice (IRN) on IRP: Complete 2026 Guide

With GST e-invoicing compliance progressively encompassing smaller businesses, generating a valid Invoice Reference Number (IRN) is now a non-negotiable daily operation. Unlike standard commercial billing, you can no longer simply print a PDF from your accounting software and hand it to a corporate buyer. A legally valid B2B invoice requires real-time digital validation from a government-authorized Invoice Registration Portal (IRP). For finance managers and business owners, transitioning from traditional invoicing to an IRP-compliant digital workflow is critical to maintaining uninterrupted supply chains, ensuring buyer Input Tax Credit (ITC), and avoiding penalties.

A common misconception is that businesses must log into a government website to manually type out their invoices. In reality, the e-invoicing system is designed for machine-to-machine integration. The process involves structuring your existing billing data into a standardized JSON payload and transmitting it to the IRP for instant validation. This comprehensive procedural guide walks you through the exact five-step workflow to **generate an e-invoice**, dissects the anatomy of the IRN and QR code, outlines available integration modes, and details the strict cancellation protocols required for 2026 GST compliance.

What is an E-Invoice, IRN, and IRP?

Before executing the workflow, it is crucial to understand the distinct technical terms that define the e-invoicing architecture under Rule 48(4) of the CGST Rules.

• E-Invoice: A standard tax invoice that has been successfully registered, validated, and digitally signed by the government portal. The government does not generate the invoice for you; you generate it in your ERP, and the government validates it.
• IRP (Invoice Registration Portal): The authorized gateway—such as einvoice1.gst.gov.in or portals operated by NIC, Clear, or Jio—where invoice data is uploaded for validation.
• IRN (Invoice Reference Number): A unique 64-character alphanumeric hash generated by the IRP using the RSA256 encryption algorithm. It ensures no duplicate invoices are ever submitted.

The Anatomy of the IRN Hash

The IRP generates the 64-character IRN by combining four specific data points from your invoice payload. If any of these four elements match a previously generated invoice, the portal will reject the request as a duplicate:

1. Supplier GSTIN
2. Financial Year (e.g., 2026-27)
3. Document Type (INV for Invoice, CRN for Credit Note, DBN for Debit Note)
4. Document Number (Your internal invoice number)

Mandatory Prerequisites to Generate IRN

To successfully communicate with the Invoice Registration Portal, your business must ensure the following prerequisites are met:

• IRP Portal Registration: Registration on the main GST Portal does not automatically grant IRP access. You must create separate API login credentials on the e-invoice portal.
• E-Invoicing Enablement: Your GSTIN status on the IRP must show as “Enabled for e-Invoicing”.
• ERP Readiness: Your billing software must be capable of exporting data in the standardized eINV-01 JSON schema, or you must be prepared to use the offline Excel utility.
• Accurate Master Data: Ensure all customer GSTINs, pin codes, state codes, and HSN codes are perfectly accurate. The IRP will instantly reject payloads containing invalid HSN formats or mismatched pin/state codes.

Step-by-Step Process to Generate an E-Invoice (IRN)

The generation of an e-invoice follows a precise, sequential flow of data from the supplier’s ecosystem to the government’s server and back.

Step 1: Create the Invoice in Your ERP

Generate a standard tax invoice within your ERP system or accounting software exactly as you normally would. Ensure all mandatory fields—Supplier GSTIN, Buyer GSTIN, Invoice Date, Invoice Number, HSN Code, Item Value, Tax Rate, and Place of Supply—are meticulously filled out.

Step 2: Convert Invoice Data into JSON Payload

The IRP cannot read PDF, Word, or raw Excel files; it only reads structured JSON (JavaScript Object Notation). Your software must map the invoice data to the official eINV-01 schema and generate a JSON file. If you use a modern ERP (like TallyPrime, Zoho, or SAP), this conversion happens automatically in the background.

Step 3: Upload JSON to the Invoice Registration Portal

Push the JSON payload to the IRP. This transmission occurs either via direct API integration, through a GST Suvidha Provider (GSP), or by manually uploading the file via the government’s offline bulk generation tool.

Step 4: IRP Validation and Hash Generation

Upon receiving the JSON, the IRP performs rapid validation checks. It confirms the supplier’s eligibility, verifies the buyer’s GSTIN, cross-checks HSN validity, and ensures the invoice number hasn’t been used previously in the financial year. Upon successful validation, the IRP generates the 64-character IRN and digitally signs the file.

Step 5: Return of Signed JSON and Auto-Population

The IRP returns a digitally signed JSON payload containing the IRN and a QR code back to your ERP system. Simultaneously, the IRP transmits the validated data to the GST Common Portal to auto-populate Table 4 of your Form GSTR-1, and to the E-Way Bill portal to generate Part-A of the E-Way Bill (if requested in the payload).

Available Integration Methods for Generating IRN

Businesses have varied operational volumes and IT budgets. The government provides multiple pathways to connect to the IRP, ensuring both MSMEs and large corporations can comply seamlessly.

Anatomy of the E-Invoice QR Code

A legally compliant e-invoice must display the digitally signed QR code generated by the IRP. Without this scannable code, the printed invoice is considered invalid, regardless of whether the IRN is typed out. The QR code acts as an offline verification tool for tax officers and contains the following encapsulated data:

• GSTIN of Supplier and Recipient
• Invoice Number and Document Date
• Invoice Value (Total Taxable Value and Gross Tax Amount)
• Total Number of Line Items
• Main HSN Code (The item carrying the highest taxable value)
• The Unique 64-character IRN Hash

How to Cancel an E-Invoice (IRN)

Mistakes happen—wrong tax rates, incorrect buyer details, or cancelled orders. However, correcting an e-invoice is bound by strict statutory timelines. E-invoices cannot be partially amended on the IRP; they must be fully cancelled.

• The 24-Hour Rule: You can only cancel an IRN directly on the Invoice Registration Portal within 24 hours of generation.
• E-Way Bill Constraint: If a valid E-Way Bill is attached to the IRN, the IRP will block cancellation. You must cancel the E-Way bill first, then cancel the IRN.
• Post 24-Hour Protocol: If the 24-hour window lapses, you cannot cancel the IRN on the IRP. Instead, you must manually amend or delete the corresponding entry in Form GSTR-1 on the main GST portal before filing your monthly returns. You must then generate a new invoice with a distinct document number.

Frequently Asked Questions (FAQs)

About this article: Researched using official NIC documentation, IRP API schemas, and Delhi Tax Solutions’ technical tax advisory team. Last updated September 2026.

Disclaimer: This article provides general technical and procedural information regarding the IRP portal and is not a substitute for tailored professional IT or tax advisory.