E-invoicing in India for small businesses: who, how, when

In India, e-invoicing under GST means sending each B2B invoice to a government Invoice Registration Portal (IRP) and printing the signed QR code it returns. It is compulsory for any business whose aggregate turnover exceeded ₹5 crore in any financial year since 2017-18, and since 1 April 2025 businesses at ₹10 crore or more must report each invoice within 30 days of its date.

This guide is for owners and finance heads of small and mid-size firms near or above those lines. For a short definition of the IRN, see our glossary entry on e-invoicing in India. This is general information, not legal or tax advice; check current notifications with your CA before acting.

Does your business have to e-invoice?

CBIC Notification 10/2023 Central Tax, dated 10 May 2023, set the current threshold: from 1 August 2023, every registered person whose aggregate turnover exceeded ₹5 crore in any preceding financial year from 2017-18 must e-invoice. Because the test looks at any year since 2017-18, crossing ₹5 crore once is enough, even if turnover falls later.

It covers B2B invoices, credit notes, debit notes and exports. Supplies to SEZs and deemed exports are covered too. B2C invoices do not get an IRN, and nor do bills of supply for nil-rated or exempt supplies.

The scope widens on 1 January 2027. Notification 04/2026 Central Tax, dated 26 October 2026, adds two kinds of self-invoice: supplies received from unregistered persons where you pay tax on reverse charge, and import of services. If you buy from unregistered suppliers under reverse charge, your billing process needs to change before January.

How do you get an IRN and QR code?

1. Prepare the invoice in your billing or accounting software with the fields in the INV-01 schema. Businesses without software can use the free offline bulk generation tool from the e-invoice portal.
2. Send it to an IRP as JSON: through your software's direct API, through a GST Suvidha Provider (GSP), or by uploading the offline tool's file. GSTN lists six operational IRPs (two run by NIC, plus Cygnet, Clear, EY and IRIS); if one is down, another can be used.
3. The IRP validates it. It rejects a duplicate (the same supplier GSTIN, document number, document type and financial year) and other errors, with an error code.
4. The IRP returns signed JSON with a 64 character Invoice Reference Number (IRN) and a signed QR code. It does not return a PDF; your software makes the printable invoice.
5. Print the QR code on the invoice. It is a mandatory particular under Rule 46 of the CGST Rules. Printing the IRN itself is optional, since the QR code contains it.
6. The data flows on. It is auto-populated into your GSTR-1, and if you sent transport details, the e-way bill can be generated from the same data.

What is the 30 day limit?

GSTN's advisory of 5 November 2024 says that from 1 April 2025, taxpayers with aggregate annual turnover of ₹10 crore and above cannot report an e-invoice older than 30 days on the IRP. It applies to invoices, credit notes and debit notes. GSTN's own example: an invoice dated 1 April 2025 cannot be reported after 30 April 2025. The IRP's validation simply refuses it.

The same advisory says there is no such restriction below ₹10 crore "as of now". The limit started with ₹100 crore businesses after a September 2023 advisory, so plan as if it may come down again.

What happens if you miss it?

Rule 48(5) of the CGST Rules says an invoice issued by a notified person in any other manner "shall not be treated as an invoice". The government FAQ puts it plainly: the document "becomes legally valid only with an IRN". That is a problem for your customer, who needs a valid tax invoice, as much as for you. The same FAQ points to section 122 of the CGST Act for penalties.

If you are at ₹10 crore or more and the 30 day window has closed, the IRP will not accept the invoice and the advisory offers no late route. Talk to your CA before that happens rather than after.

Mistakes have their own rules:

• Cancellation is possible on the IRP within 24 hours of reporting, but not if a connected e-way bill is active. There is no partial cancellation.
• A cancelled invoice number cannot be reused for another IRN, because the IRN is built from it.
• Amendments are not possible on the IRP. Changes are made on the GST portal through GSTR-1, and they are flagged to the officer.

What can a small business automate?

The IRP is built for machine-to-machine reporting, so most of the work around it can be automated:

• IRN generation from your billing system, by API or through a GSP, so nobody uploads files by hand.
• Checks before sending: GSTIN format, duplicate numbers, HSN codes and tax maths, so the IRP rejects less.
• A 30 day watch: a daily list of invoices without an IRN, oldest first.
• Error handling: IRP error codes read and routed to the person who can fix the data.
• Matching IRNs back to the books, including Tally, and checking that GSTR-1 agrees.

What stays with a person: approving the invoice, cancellations and credit notes. That is how we build these flows in our GST and accounting automation work: the automation proposes, a person confirms. The same discipline applies on the purchase side, covered in our guide to GSTR-2B reconciliation in Tally.

Getting ready

If you are near ₹5 crore, or buy from unregistered suppliers under reverse charge, check that your billing software can call an IRP and that invoice numbering is clean. CA firms handling many clients can see how we work on our accounting and CA firms page. Bring one month of invoices and we will show you what can be automated. Book a consultation.