Invoice Reference Number (IRN) in GST
Understand the IRN full form, how an Invoice Reference Number is generated, where to find it on an e-invoice and how to verify the registered document.
What Is an Invoice Reference Number (IRN)?
An Invoice Reference Number (IRN) is a unique 64-character identifier generated by an authorised Invoice Registration Portal (IRP) when an eligible tax invoice, credit note or debit note is successfully registered under India’s GST e-invoicing system.
IRN stands for Invoice Reference Number. It identifies a registered e-invoice document and helps prevent duplicate registration. The IRN is different from the supplier’s own invoice number. Learn more about the GST e-invoicing system.
What Is the Full Form of IRN in GST?
IRN full form: Invoice Reference Number. In GST, it refers to the 64-character hexadecimal hash associated with a document registered through an IRP. It is issued as part of the successful e-invoice registration response.
How Is an IRN Number Generated?
The IRP generates an IRN using the SHA-256 hashing algorithm and identifying document information. Once the submitted e-invoice data passes validation, the IRP returns the IRN, an acknowledgement and a digitally signed QR code.
Businesses do not normally calculate the IRN manually. They submit the required invoice data through an authorised IRP, a supported offline utility or compatible software integration.
What Parameters Are Used to Generate an IRN?
The unique document identification is based on four elements:
- Supplier GSTIN: GST registration number of the supplier.
- Financial year: Financial year relating to the document date.
- Document type: Tax invoice, debit note or credit note.
- Document number: The number assigned by the supplier.
Using these elements, the system prevents a second IRN from being registered for the same document identity.
IRN Number Example in GST
Consider this illustrative invoice record:
| Parameter | Example |
|---|---|
| Supplier GSTIN | Sample GSTIN (illustration only) |
| Financial year | 2026–27 |
| Document type | Tax invoice |
| Document number | INV-105 |
When a valid document containing the complete required details is accepted by an IRP, the portal returns its actual IRN. The example above does not represent a registered invoice or a real portal-issued IRN.
Where to Find the IRN Number on an Invoice
After successful registration, find the IRN in the response from the IRP or in your billing software’s registered e-invoice details. Some invoice layouts display the value in a field labelled IRN or Invoice Reference Number.
- Open the successfully registered e-invoice or the related IRP acknowledgement.
- Look for the IRN field and the acknowledgement details.
- Check the signed QR code included on the e-invoice; it carries information including the IRN.
Editorial image placement: Insert a redacted, verified sample e-invoice here with the IRN field and signed QR code labelled. Do not substitute a fabricated valid-looking QR code.
Difference Between Invoice Number and IRN Number
An invoice number is assigned by the supplier. The IRN is returned by the Invoice Registration Portal after registration.
| Basis | Invoice number | IRN |
|---|---|---|
| Issued by | Supplier or billing software | Authorised IRP |
| Purpose | Identifies the invoice in business records | Identifies the registered e-invoice document |
| Format | Supplier-defined, within GST invoicing rules | 64-character hexadecimal hash |
| When created | During invoicing | After successful IRP validation and registration |
When Is the Invoice Reference Number (IRN) Generated?
An IRN is generated when an eligible document is successfully reported to an authorised IRP. The GST e-invoicing mandate generally covers taxpayers whose aggregate annual turnover has exceeded ₹5 crore in any financial year from FY 2017–18, subject to exclusions and the applicable rules. See the separate e-invoice limit and applicability guide for detailed eligibility.
Important IRN Reporting Time Limit
From 1 April 2025, taxpayers with aggregate annual turnover of ₹10 crore or more are subject to a 30-day reporting restriction for eligible invoices, credit notes and debit notes on the IRP. This time-limit threshold is separate from the ₹5 crore e-invoicing applicability threshold. Check the latest official advisory before relying on time-sensitive compliance guidance.
How to Generate an IRN Number for an E-Invoice
For an eligible document, the usual registration process is:
- Prepare an invoice, debit note or credit note containing the required GST fields.
- Submit the document details through an authorised IRP or integrated e-invoicing software.
- Correct any validation errors returned by the portal.
- On successful registration, receive the 64-character IRN, acknowledgement and signed QR code.
- Store the registered document details and include the signed QR code on the invoice as applicable.
For a full procedure, see e-invoice registration and generation. For batch processing, see bulk IRN generation.
How to Check or Verify an IRN Number in GST
You can check registered e-invoice information by verifying the digitally signed QR code using the official e-invoice verification app or an authorised portal verification facility.
- Open an official, supported QR-code verification tool.
- Scan the signed QR code on the registered e-invoice.
- Review the verified information, such as supplier GSTIN, document number, document date and IRN.
- Compare those details with the invoice you received.
If details do not match, ask the supplier to confirm the registration and the invoice. A QR-code verification procedure should not be confused with registering a new IRN. See the e-invoice QR code scanner guide.
Common IRN Generation Errors and How to Avoid Them
If IRN generation fails, examine the portal response before submitting again.
| Issue | What to check |
|---|---|
| Duplicate document | Check whether an IRN already exists for the supplier, financial year, document type and number. |
| Invalid GSTIN | Verify relevant GSTIN details and status. |
| Document data error | Review mandatory fields, dates, document type and tax values. |
| Reporting window exceeded | Check document date against restrictions applicable to the taxpayer. |
For specific portal messages, refer to common e-invoice errors and codes.
What Is the Difference Between an IRN and a QR Code?
The IRN is the unique identifier of the registered e-invoice document. The digitally signed QR code contains key invoice details, including the IRN, and is used to verify those details and the authenticity of the signed information. They are related but are not interchangeable.
Frequently Asked Questions
Does an IRN expire after 24 hours?
No. The IRN does not automatically expire after 24 hours. The commonly cited 24-hour window concerns cancellation through the IRP, subject to applicable portal conditions.
Can an IRN be cancelled?
An IRN can generally be cancelled on the IRP within 24 hours of reporting, subject to the rules and any linked e-way bill restrictions. After that period, use the applicable GST return or correction process rather than attempting a late IRP cancellation. See how to cancel an e-invoice.
Can the same invoice number be used to generate another IRN?
Not for the same combination of supplier GSTIN, financial year, document type and document number. Cancelling an IRN does not make that document identity available for re-registration.
How is the financial year determined for IRN generation?
It follows the date of the document. For example, a document dated 15 October 2026 belongs to financial year 2026–27.
Is an IRN required for every GST invoice?
No. The requirement applies to relevant document types and transactions of taxpayers covered by the e-invoicing mandate, subject to exemptions.
Last reviewed: 21 October 2026
Official references: GST e-invoice portal; GST Portal; applicable CBIC notifications and IRP advisories. Check the official portals for subsequent changes.