What is e-invoicing under GST?
Short answer
E-invoicing under GST is the system where B2B invoices are uploaded to a government Invoice Registration Portal (IRP), which validates them and returns a unique Invoice Reference Number (IRN) and a digitally signed QR code. It is mandatory for businesses whose annual aggregate turnover exceeds ₹5 crore in any year since 2017-18.
Updated 2026-06-03 · 399Apps · General GST information, not tax advice
How to generate an e-invoice: step by step
You do not type invoices into a government site. Your billing software prepares the data and exchanges it with the IRP automatically.
- 1
Create the invoice with all GST fields
Raise the B2B invoice in your accounting/billing software with GSTIN, HSN/SAC, taxable value and tax split — exactly as on a normal tax invoice.
- 2
Generate the e-invoice JSON
The software converts the invoice into the standard e-invoice schema (Form INV-01 / JSON).
- 3
Upload to the IRP
The JSON is sent to an Invoice Registration Portal (the NIC IRP or another approved IRP) over API.
- 4
Receive the IRN and signed QR code
The IRP validates the invoice, generates a unique 64-character Invoice Reference Number (IRN), digitally signs it and returns a QR code.
- 5
Share the invoice with the IRN and QR
Print or send the invoice showing the IRN and signed QR code — this is now the legally valid B2B tax invoice.
- 6
Auto-flow to GST returns and e-way bill
The reported invoice auto-populates your GSTR-1, and an e-way bill can be generated from the same data for movement of goods.
What is e-invoicing under GST?
E-invoicing (electronic invoicing) does not mean generating an invoice on a government website. It means reporting a B2B invoice you have already created to a government Invoice Registration Portal (IRP) in a standard format, so the portal can authenticate it and issue an Invoice Reference Number (IRN) and a signed QR code. Only an invoice carrying a valid IRN is treated as a legal tax invoice for businesses covered by the rule.
Who must comply: the turnover threshold
E-invoicing applies based on aggregate annual turnover, which has been lowered in phases since 2020:
- • Mandatory for businesses with aggregate turnover above ₹5 crore in any financial year from 2017-18 onwards (effective 1 August 2023).
- • Applies to B2B supplies, supplies to SEZ, exports, and credit/debit notes.
- • It does not apply to B2C invoices (though a dynamic QR code applies separately for large B2C suppliers).
- • Exempt categories include banks and financial institutions, insurers, goods transport agencies, passenger-transport services, cinema/multiplex admission, and SEZ units (not SEZ developers).
How e-invoicing works: IRP, IRN and QR code
The flow is: your software creates the invoice, converts it to the e-invoice JSON schema, and sends it to an IRP. The IRP checks for duplicates, validates the structure, generates the unique IRN, digitally signs the payload, and returns a QR code that encodes the key invoice details. The signed invoice then auto-populates GSTR-1 and can feed the e-way bill system — removing duplicate data entry.
The 30-day reporting time limit
To keep reporting timely, the GST Network applies a time limit for uploading invoices to the IRP. From 1 April 2025, taxpayers with an aggregate annual turnover of ₹10 crore or more must report e-invoices within 30 days of the invoice date; after that window the IRP will reject the invoice. Businesses near the threshold should report promptly rather than batch invoices at month-end.
Benefits of e-invoicing
Because the invoice is authenticated at source, e-invoicing reduces fake invoices and ITC fraud, removes duplicate data entry across GSTR-1 and the e-way bill, speeds up your buyers’ input tax credit (the data appears in their GSTR-2B), and cuts reconciliation effort at month-end.
How 399Apps helps
Nidhi Books (by 399Apps) supports e-invoicing and e-way bill generation above the applicable thresholds: it builds the e-invoice JSON, fetches the IRN and QR code from the IRP, and prints them on the invoice — so a ₹5-crore-plus business stays compliant without a separate utility or manual uploads.
What is e-invoicing under GST — frequently asked questions
What is the turnover limit for e-invoicing under GST? +
Is e-invoicing required for B2C invoices? +
What is an IRN in e-invoicing? +
Is there a time limit to generate an e-invoice? +
Who is exempt from e-invoicing? +
GST billing, returns & e-invoicing — done automatically
Nidhi Books raises GST-compliant invoices and prepares GSTR-1 and GSTR-3B exports, with unlimited users from ₹399/month for your first app (+₹99/month per add-on, prices exclude GST). Free for 14 days.