1. What is E-Invoice IRN?
IRN stands for Invoice Reference Number. It is a 64-character unique hash generated by the National Informatics Centre (NIC) — a government body under the Ministry of Electronics and Information Technology — for every B2B tax invoice.
Here is what a real IRN looks like:
Invoice Reference Number (IRN)
a197d13e6f7f48e7c5ef9a66a06ca2ded2a2c63a8b4a3f1e9b12c7d0e8f6a4b5
Acknowledgement Number
132410100123456
Acknowledgement Date
2026-05-01 09:32:17
The IRN is generated by sending your invoice data (in a standardized JSON format) to NIC's Invoice Registration Portal (IRP). NIC validates the data, assigns the IRN, and returns a digitally signed response containing the IRN, an Acknowledgement Number, an Acknowledgement Date, and a digitally signed QR code.
All four of these must be printed on your invoice PDF — this is what makes the invoice legally valid under GST for B2B buyers above the threshold.
Plain-English summary: NIC is the government's digital stamp office. When you issue a B2B invoice, you submit it to NIC online. NIC checks it, stamps it with a unique number (the IRN), and gives it back to you. That stamp on your invoice PDF proves it is a valid, government-registered invoice.
2. Who Needs to Generate IRN?
As of 2026, E-Invoice IRN is mandatory for all GST-registered businesses with annual aggregate turnover above ₹5 Crore. The threshold is assessed across all GSTINs registered under a single PAN.
Which invoices require IRN?
- B2B tax invoices — invoices issued to buyers who have a GSTIN. This is the primary use case.
- Credit notes linked to B2B invoices
- Debit notes linked to B2B invoices
- Export invoices — invoices for goods/services exported outside India
- Invoices to SEZ units (Special Economic Zones)
Which invoices do NOT require IRN?
- B2C invoices — invoices to buyers without a GSTIN (retail consumers)
- Delivery challans
- Proforma invoices
- Export invoices for services in some cases (check current CBIC clarifications)
- Financial or non-GST invoices
Important: The ₹5 Crore threshold applies to your aggregate annual turnover across all your GSTINs under one PAN — not per-GSTIN. If you have two businesses under the same PAN with ₹3 Crore each, your aggregate is ₹6 Crore and both GSTINs must generate IRN. Consult your CA if you are close to the threshold.
3. What Happens If You Don't Generate IRN?
An invoice issued without an IRN — when you are above the threshold — is treated as an invalid invoice under GST law. The practical consequences are significant:
- Buyer cannot claim ITC: Your buyer's Input Tax Credit claim for that invoice fails. If they discover this during their own audit or GSTR-2B reconciliation, they will come back to you demanding a valid invoice — or a credit note.
- NIC portal rejection: If you try to generate the IRN after 24 hours from the invoice date/time, the NIC API will reject the request. The invoice cannot be retrospectively validated.
- GST notice: Non-compliance with E-Invoice requirements can lead to a GST notice under Section 122 of the CGST Act for issuance of a false invoice. In practice, enforcement is escalating.
- E-Way Bill dependency: For goods movement above ₹50,000 in value, the E-Way Bill system automatically pulls data from the IRN once generated — this eliminates duplicate data entry. Without IRN, you lose this automation and must enter E-Way Bill data manually.
4. What It Looks Like on Your Invoice
Once you generate the IRN, four pieces of information must appear on your invoice PDF:
| Item | What it is | Where it comes from |
|---|---|---|
| IRN | The 64-character unique hash identifying this invoice | NIC IRP response |
| Ack Number | 15-digit acknowledgement number from NIC | NIC IRP response |
| Ack Date | Date and time NIC registered the invoice | NIC IRP response |
| Digitally signed QR code | A QR code containing the invoice's key data, digitally signed by NIC — scannable by GST officers | NIC IRP response |
A GST officer can scan the QR code on your invoice using the CBIC Verify App and instantly verify that the invoice is registered with NIC, that the data matches, and that the digital signature is valid. This is what makes the E-Invoice system tamper-proof.
5. How to Generate IRN
There are three methods. The correct method depends on your invoice volume and systems:
Method 1: NIC's own web portal (manual)
You log in to einvoice1.gst.gov.in and enter your invoice data manually. NIC returns the IRN. Suitable for businesses with very few invoices (under 5 per month). Not practical for any business doing regular invoicing.
Method 2: ERP or billing software with direct NIC API integration
Your billing software sends the invoice JSON to the NIC IRP automatically when you create the invoice. NIC responds with the IRN, Ack Number, Ack Date, and QR code. Your software prints all four on the invoice PDF — without you doing anything manually. This is the right approach for any business doing more than a handful of B2B invoices per month.
PragatiCRM's GST invoicing module uses this method — one click generates the invoice and submits it to NIC simultaneously. The IRN and QR code appear on the PDF automatically.
Method 3: GSP (GST Suvidha Provider) integration
A GSP is a licensed intermediary that connects your system to NIC. GSPs typically charge a per-invoice fee or a monthly subscription. For most businesses, this adds unnecessary cost and complexity — direct NIC API integration in modern billing software makes GSP unnecessary.
Key principle: IRN generation should happen at the moment of invoice creation — not after. If your billing software creates the invoice first and asks you to "upload to NIC later," there is a risk of missing the 24-hour window or creating mismatches. Look for software where IRN is generated as part of invoice creation, not as a separate step.
6. The 24-Hour Cancellation Window
An IRN can be cancelled — but only within 24 hours of generation. After 24 hours, the IRN is permanently locked in the NIC system.
If you need to reverse the transaction after the 24-hour window has closed:
- Issue a credit note for the full amount of the original invoice
- The credit note also requires IRN generation (it is linked to the original invoice's IRN)
- The original invoice remains in the NIC system — it cannot be deleted or modified
This 24-hour window is why it matters that your billing software generates the IRN at invoice creation. If you generate the invoice on Monday and only submit it to NIC on Wednesday — the submission will fail.
A common mistake: Generating invoices in batches at the end of the month and then trying to get IRNs for them all at once. Invoices more than 24 hours old cannot get an IRN. The correct approach: IRN at the time of invoice creation, every time.
7. Threshold History — and Why It May Go Lower
The E-Invoice mandate started in October 2020 with a very high threshold and has been progressively lowered:
- Oct 2020 ₹500 Crore Large enterprises only — top 500 businesses in India
- Jan 2021 ₹100 Crore Extended to large and mid-large businesses
- Apr 2021 ₹50 Crore Mid-market businesses included
- Oct 2022 ₹10 Crore Extended significantly — many MSMEs now included
- Aug 2023 ₹5 Crore Current threshold — covers a large part of the formal MSME sector
- Next? ₹2 Crore? No official announcement as of May 2026 — but the direction of travel is clear. Businesses between ₹2–5 Crore should prepare now.
If your turnover is between ₹2 Crore and ₹5 Crore, it is worth ensuring your billing software supports IRN generation today — so you are not scrambling when the threshold drops to include you. Switching billing software mid-compliance-deadline is not a position you want to be in.
For context on how MCA compliance and CERT-In requirements are similarly expanding — see our MCA Audit Trail guide.
8. How PragatiCRM Handles E-Invoice IRN
If you are above the ₹5 Crore threshold — or approaching it — here is what E-Invoice in PragatiCRM looks like in practice:
- When you create a B2B tax invoice, PragatiCRM submits the invoice JSON to the NIC IRP automatically
- NIC responds with the IRN, Ack Number, Ack Date, and signed QR code — in under 2 seconds in most cases
- All four are printed on the invoice PDF automatically — no manual copy-paste
- If NIC returns an error (invalid GSTIN, duplicate invoice number, etc.), PragatiCRM shows the error in plain English and lets you correct and resubmit
- E-Way Bill data is auto-pulled from the IRN for goods movements — no duplicate entry
- E-Invoice is off by default for businesses below the threshold. You enable it with one toggle when you cross ₹5 Crore.
The entire E-Invoice workflow — from invoice creation to IRN on the PDF — takes the same time as creating any other invoice. No separate step. No manual JSON building. No GSP middleman.
Approaching ₹5 Crore? Your billing software needs to be ready.
If you are approaching the E-Invoice threshold — or already above it — your billing software should handle IRN generation automatically. See how PragatiCRM does it — including a live demo of the IRN appearing on the invoice PDF.
See PragatiCRM's GST invoicing →Frequently Asked Questions
Who needs to generate E-Invoice IRN?
All GST-registered businesses with annual aggregate turnover above ₹5 Crore must generate E-Invoice IRN for all B2B tax invoices, credit notes, and debit notes. The threshold applies to all GSTINs under a single PAN. B2C invoices (to unregistered buyers) do not require IRN.
What happens if I issue a B2B invoice without an IRN?
An invoice issued without an IRN is considered invalid under GST law if you are above the threshold. Your buyer cannot claim Input Tax Credit (ITC) on that invoice. The NIC API will reject any attempt to generate IRN after 24 hours from the invoice time. You may receive a GST notice for non-compliance.
Can I cancel an IRN after generating it?
Yes — an IRN can be cancelled only within 24 hours of generation. After 24 hours, the IRN is locked. If you need to reverse the transaction after the 24-hour window, you must issue a credit note for the full invoice amount. The original IRN remains valid and linked to the credit note.
Do I need a GSP to generate IRN?
No — you do not need a GSP. IRN can be generated via the NIC web portal (manual, impractical for volume), via billing software with direct NIC API integration (recommended), or via a GSP (adds cost and complexity — not necessary for most businesses).
Is there a threshold below which IRN is not required?
Yes — the current threshold is ₹5 Crore annual aggregate turnover. Below this threshold, IRN is not legally required. However, the threshold has been reduced repeatedly from ₹500 Crore in 2020, and further reductions are expected. Businesses between ₹2–5 Crore should prepare now.