E-Invoicing Under GST: Threshold, IRN, QR Code and 2FA Guide

E-invoicing requires eligible businesses to report each invoice to the government’s Invoice Registration Portal (IRP) and receive an Invoice Reference Number (IRN) with a digitally signed QR code in return. Since 1 August 2023, the mandate applies to every registered person with aggregate annual turnover above ₹5 crore. This guide covers the threshold, generation options, reporting deadlines, exemptions and penalties as they stand in 2026.

The ₹5 Crore Threshold: How the Net Widened

E-invoicing was introduced for very large taxpayers and then walked down the turnover ladder in steps, each made effective from a fixed date:

Eligibility is measured on aggregate turnover in the preceding financial year, computed across the GSTINs registered on the same PAN. Once a taxpayer crosses the threshold, e-invoicing applies permanently, even if turnover falls in a later year, so growing businesses should build the capability before the mandate bites.

IRN and the Signed QR Code

The IRN is a unique identifier generated as a hash of the supplier GSTIN, recipient GSTIN and invoice number and date, which prevents the same document being registered twice. The IRP returns the IRN together with a digitally signed QR code carrying the key invoice fields, and the invoice is not a valid tax document until it carries both.

Businesses have three practical routes to the IRP: direct API or GSP integration for high-volume billing, the e-invoice portal’s bulk generation tool for uploading JSON files, and generation through the portal interface itself. Whatever the route, keep the returned QR code and IRN embedded on the final invoice issued to the buyer, since enforcement checks increasingly verify them at the point of sale and transit.

The 30-Day Reporting Window for Larger Taxpayers

From 1 April 2024, taxpayers with AATO of ₹10 crore or more must report invoices, credit notes and debit notes to the IRP within 30 days of the document date. The window stops back-loading a month of invoices in one go, so billing systems need to push documents out as they are issued rather than batching them at month end.

Who Is Exempt From E-Invoicing

Several categories remain outside the mandate even above the threshold, including:

• Banks, non-banking financial companies and insurers.
• Goods transport agencies (GTA) and passenger transport service providers.
• Cinema ticket sales and other notified service categories.
• Certain special-category registrations such as SEZ units, among others notified by the government.

Exemption lists are amended from time to time, so confirm the current notification for your registration class before assuming you are outside the net.

Penalties: No IRN, No Valid Invoice

An invoice without a valid IRN is not a valid tax document for a mandated taxpayer. Issuing such an invoice attracts a penalty of ₹50,000, split as ₹25,000 under CGST and ₹25,000 under SGST. The damage rarely stops at the penalty: the buyer’s input tax credit on an invalid document is exposed, and disputes with customers over invoice validity are common.

Two-Factor Authentication and Common Validation Errors

Through 2025, the e-invoice and e-way bill systems moved to two-factor authentication (2FA) for portal logins, adding an OTP step beyond the password. Finance teams should register mobile numbers for the users who generate documents, because a locked-out approver can stall dispatch on billing day. Our earlier post on 2-factor authentication in GST e-invoice and e-way bill explains the rollout.

Most generation failures fall into a few buckets. Watch for:

• Duplicate IRN: the same document number and date already reported, so correct the document series or check for earlier uploads.
• Date and amount mismatches: the JSON payload disagrees with the printed invoice, so align billing software output with the document.
• Invalid buyer GSTIN: the recipient identification fails portal validation, so verify customer registrations with a GST number verification tool before the first invoice.

A sound workflow is simple: verify master data, generate the IRN at invoicing time, confirm the QR code prints on the document, and reconcile the IRP register against your sales register monthly. Where e-invoices feed transport paperwork, validate distances and consignment values alongside the e-way bill validity calculator so the two systems agree.

Key Takeaways

• E-invoicing is mandatory above ₹5 crore AATO, a threshold that stepped down from ₹500 crore to ₹5 crore by 1 August 2023.
• Every mandated invoice needs an IRN from the IRP and a digitally signed QR code; without them the invoice is invalid.
• Taxpayers with AATO of ₹10 crore or more must report documents within 30 days of the document date, effective 1 April 2024.
• The penalty for issuing an invoice without an IRN is ₹50,000, split equally between CGST and SGST.

Frequently Asked Questions

Whose turnover counts for the ₹5 crore threshold?

Aggregate turnover in the preceding financial year across the GSTINs on the same PAN. Once crossed, the mandate continues even if turnover later drops below the limit.

Can I issue an invoice first and report it later?

Taxpayers with AATO of ₹10 crore or more must report within 30 days of the document date. Other mandated taxpayers should still report at invoicing time, since an invoice without an IRN is not a valid tax document.

What is the penalty for an invoice without an IRN?

₹50,000 per document, split as ₹25,000 under CGST and ₹25,000 under SGST, and the document is treated as invalid for tax purposes.

Is two-factor authentication compulsory on the e-invoice portal?

The 2025 rollout made 2FA the operating norm for the e-invoice and e-way bill portals, so keep registered mobile numbers current for all users. Check our detailed 2FA post for the specifics of the rollout.

Do exempted categories still need invoices?

Yes. Exempted taxpayers issue ordinary tax invoices; they simply do not register them for an IRN. Their customers may generate e-way bill Part A using their own details where required.

What if I upload wrong invoice data to the IRP?

Correct the data and re-submit, remembering that the IRN hash blocks the same document from being registered twice. Where a wrong document has already been registered, use the portal’s cancellation and amendment processes within their limits.

Disclaimer: Tax laws change frequently. Verify current rates and deadlines on the official portals (incometax.gov.in, gst.gov.in) or consult a qualified professional before acting.