In short
GST e-invoicing means reporting each B2B invoice to a government Invoice Registration Portal (IRP) before it reaches the buyer. The IRP checks the invoice, gives it a 64-character Invoice Reference Number (IRN), signs it and returns a QR code that must be printed on the invoice. It applies to businesses whose aggregate turnover has exceeded ₹5 crore in any year since 2017-18. For most businesses this is a job for the ERP or billing software, not the website.
Who it applies to
- Threshold: aggregate turnover above ₹5 crore in any financial year from 2017-18, from 1 August 2023 under Notification 10/2023-Central Tax. Turnover is counted across all GSTINs under one PAN.
- Start date: if you cross the limit in the current year, e-invoicing starts from the next financial year.
- Exempt whatever their turnover: insurers, banking companies, financial institutions including NBFCs, goods transport agencies, passenger transport providers, multiplex cinema admission services, SEZ units, government departments and local authorities, and OIDAR providers registered under Rule 14.
- Documents covered: tax invoices, credit notes and debit notes for B2B supplies and exports.
- Not covered: B2C sales, delivery challans, bills of supply, bills of entry, ISD invoices, imports, and nil-rated or exempt supplies.
Guides updated in September 2026 still give the ₹5 crore threshold. Reports of a lower limit have not been backed by a notification, so check CBIC notifications before relying on any change.
What it means for your website
Very little for most businesses. A public website is not an invoicing system, and B2C sales are outside e-invoicing. Two cases matter:
- B2B online sales. If your store sells to GST-registered buyers, collect and validate the buyer’s GSTIN at checkout. The invoice your system issues must then carry an IRN and QR code.
- Very large B2C sellers. Businesses with aggregate turnover above ₹500 crore must print a dynamic QR code on B2C invoices, including those sent online.
What it means for your software
Deciding which documents need an IRN
The ERP must know, per GSTIN, whether e-invoicing applies, and per document, whether it is in scope. Tag each customer as B2B, B2C, export or SEZ, and each item as taxable, nil-rated or exempt. Exempt business types should be able to switch e-invoicing off at company level.
Integration with the IRP
The ERP sends invoice data in the prescribed format to an IRP, either directly through the IRP’s APIs or through a GST Suvidha Provider (GSP). The IRP validates the data, digitally signs the invoice and returns the IRN and a signed QR code. Store both against the invoice and print the QR code. A GST invoice is valid only with a valid IRN, and the buyer’s input tax credit depends on it.
The 30-day reporting window
A GSTN advisory of 5 November 2024 says that from 1 April 2025, taxpayers with aggregate annual turnover of ₹10 crore and above cannot report invoices, credit notes or debit notes older than 30 days. The IRP rejects late documents. The ERP should generate the IRN when the invoice is created, alert on any document still unreported after a few days, and never batch e-invoices to month end.
Cancellation, credit notes and debit notes
An IRN can be cancelled on the IRP only within 24 hours, and only in full. After that, issue a credit note against the original invoice and amend GSTR-1. Build cancellation as a timed action with a clear warning, and route later corrections to the credit note workflow. Credit and debit notes need their own IRNs and fall under the same 30-day rule.
Invoice numbering
Rule 46(b) of the CGST Rules requires a consecutive serial number of at most 16 characters, in one or more series. It may contain letters, digits, hyphens and slashes, and must be unique for the financial year. Configure series per GSTIN and per financial year, and let the system check length before saving.
E-way bills
An e-way bill under Rule 138 is required when a consignment is worth more than ₹50,000. Inter-state limits are uniform; intra-state limits are set by each state. Part A is filled from a valid e-invoice, so the ERP can request the e-way bill with the IRN or soon after.
Changes from 1 January 2025 matter for the software. E-way bills can only be generated for documents dated within the last 180 days. Extensions stop at 360 days from the original generation date. An e-way bill can be cancelled within 24 hours if an officer has not verified it.
B2C dynamic QR code
Notification 14/2020-Central Tax requires businesses with aggregate turnover above ₹500 crore to print a dynamic QR code on B2C invoices, from 1 December 2020. A UPI ID linked to the payee’s bank account is enough. Where part payment has been made, the QR code should show only the balance due.
Portal logins and multi-factor authentication
The e-way bill and e-invoice portals now require multi-factor authentication. It became mandatory for turnover above ₹20 crore from 1 January 2025, above ₹5 crore from 1 February 2025 and for all users from 1 April 2025. Login needs a password plus an OTP to the registered mobile number, the Sandes app or a similar channel. Keep the registered mobile number current and decide who in the team receives the OTP.
Error handling
IRP calls fail for many reasons: schema errors, invalid GSTINs, duplicates or downtime. The ERP should validate data before sending, queue failed requests and retry them, and avoid creating two IRNs for one invoice. Every request and response should be logged against the invoice for audit.
Checklist
- Check aggregate turnover by PAN for every year since 2017-18 to confirm whether e-invoicing applies.
- Classify customers, items and transaction types in the ERP so in-scope documents are flagged.
- Connect the ERP to an IRP directly or through a GSP, and test in the sandbox.
- Generate the IRN when the invoice is created, not in a monthly batch.
- Alert on any invoice, credit note or debit note still unreported after a few days.
- Limit cancellation to 24 hours and send later corrections to credit notes.
- Set invoice series to 16 characters or fewer, unique per financial year.
- Generate e-way bills from the e-invoice and track their 180-day and 360-day limits.
- Set up multi-factor login for every portal user and keep registered mobile numbers current.
- Log every IRP request and response against the document.
How Kreon helps
We build ERPs and billing systems with GST worked out on every invoice, and we can connect them to the Invoice Registration Portal so the IRN and signed QR code are fetched as the invoice is saved. We design these integrations with validation, retries, audit logs and warnings before the 24-hour and 30-day limits pass. For an existing billing system, we can add e-invoicing or review how it handles these rules.