An e-invoice is a regular GST tax invoice that is also reported, in a standard electronic format, to an Invoice Registration Portal (IRP) run under the GST system. The portal checks it, gives it a unique Invoice Reference Number (IRN) and returns it with a digitally signed QR code. The details then flow into your GSTR-1 and, where you ask, into an e-way bill.
E-invoicing does not change what the invoice must contain. Rule 46 still decides that. It changes how the invoice is registered.
01Who must e-invoice
A registered person whose aggregate turnover crossed ₹5 crore in any financial year from 2017-18 onwards must e-invoice, as of October 2026. The threshold was brought down in steps, from ₹500 crore in 2020 to ₹5 crore from 1 August 2023.
Aggregate turnover is counted on the PAN across all states, including exempt supplies and exports. A Rajkot engineering company with three GSTINs adds the turnover of all three.
Once you cross the line in any year, the rule stays. A Morbi tile maker that had ₹5.6 crore in 2022-23 and ₹4.8 crore in 2025-26 still e-invoices.
Who is exempted
Some businesses are outside e-invoicing whatever their turnover:
- Special Economic Zone units (SEZ developers are covered)
- Insurance companies, banks and financial institutions, including NBFCs
- Goods transport agencies
- Suppliers of passenger transport services
- Suppliers of admission to cinema in multiplex screens
- Government departments and local authorities
02Which documents are covered
| Document | Covered |
|---|---|
| Tax invoices to registered buyers (B2B) | Yes |
| Credit notes and debit notes to registered buyers | Yes |
| Exports, with or without IGST | Yes |
| Supplies to SEZ units and developers | Yes |
| Deemed exports | Yes |
| Invoices to unregistered buyers (B2C) | No |
| Delivery challans, bills of supply, receipt vouchers | No |
| Self-invoices for purchases from unregistered suppliers | No |
03How it works, step by step
- Prepare the invoice in your billing software as usual, with the buyer's GSTIN, HSN codes and tax.
- Send it to an IRP, through the portal, an API, or your software's link to it. The data is sent in the standard JSON format, known as INV-01.
- The IRP checks it. It rejects duplicates, invalid GSTINs and some format errors. Each invoice number can be registered once in a financial year.
- IRN and QR code come back. The IRN is a 64-character reference. The signed QR code carries the key details.
- Print or send the invoice with the QR code on it.
- GSTR-1 is filled from the reported invoices. You still check and file GSTR-1 yourself.
- E-way bill, if needed, can be generated from the IRN by adding transport details.
04The 30-day reporting limit
If your aggregate turnover is ₹10 crore or more, invoices, credit notes and debit notes must be reported to the IRP within 30 days of the document date, as of October 2026. The portal will not accept older documents. The limit was introduced for businesses with turnover of ₹100 crore and above in 2023, and extended to ₹10 crore and above from 1 April 2025.
Example: an Ahmedabad pharma distributor with ₹14 crore turnover issues an invoice dated 3 October 2026. It must be reported by 2 November 2026. If the billing team misses that window, the portal will not register the invoice, which leaves the sale without a valid invoice. Teams that report each invoice the day it is made never meet this problem.
Below ₹10 crore, there is no fixed reporting window on the portal, but an invoice without an IRN is still not a valid invoice. The safe practice is to generate the IRN when you make the invoice.
05Cancelling and correcting
| Situation | What to do |
|---|---|
| Error found within 24 hours | Cancel the IRN on the portal and issue a fresh invoice with a new number |
| Error found after 24 hours | Issue a credit note, report it, and issue a fresh invoice if needed |
| Part of the goods returned | Issue a credit note and report it |
An IRN cannot be partly cancelled. If an e-way bill was generated from the invoice, it must be cancelled before the IRN.
06What changes in your office
For a business that bills on paper or simple software and now has to e-invoice, the work is in the data:
- Buyer GSTINs must be correct, because the portal checks them.
- HSN codes need at least 6 digits above ₹5 crore turnover.
- Invoice numbers must be unique for the year across all billing points.
- Units of quantity must use the standard codes, such as NOS, KGS and BOX.
A Surat textile trader moving to e-invoicing usually spends the first month cleaning its customer master. After that, generating the IRN adds seconds to each bill.
07What buyers check
Large buyers increasingly scan the QR code on supplier invoices before they book them. If the QR code is missing or does not verify, the bill goes back to the supplier and payment waits. For a supplier, a clean e-invoice is part of getting paid on time.
08E-invoices and e-way bills together
Where goods move and an e-way bill is needed, it can be generated from the IRN by adding the vehicle number and transporter. Part A is taken from the e-invoice, so the data is entered once.
09Checking if the rule covers you
Look at your aggregate turnover for every financial year from 2017-18. If any year was above ₹5 crore, you are covered. The e-invoice portal also lets you check the e-invoice status of a GSTIN. A business that becomes liable from 1 April must have its billing ready for that date, because invoices issued without an IRN from then on are not valid.
This guide is general information as of October 2026 and does not amount to tax advice.