GST E-Invoice: Mandatory Thresholds, Generation Process and IRN

E-invoicing under GST (Electronic Invoicing) is the process by which B2B invoices are authenticated by the Government's Invoice Registration Portal (IRP) and issued an Invoice Reference Number (IRN). Introduced in phases from October 2020, it is now mandatory for taxpayers with aggregate turnover exceeding Rs.5 crore (as of 1 August 2023).

Rollout History and Current Threshold

Exempted from E-Invoicing

• NBFC (Non-Banking Financial Companies)
• Banks and insurance companies
• GTA (Goods Transport Agencies)
• SEZ (Special Economic Zone) units
• Registered persons supplying passenger transport services
• Suppliers of cinema admission tickets
• B2C transactions (supply to unregistered buyers)

E-Invoice Generation Process

1. Prepare invoice in your accounting software (Tally, SAP, Zoho, etc.) in JSON format per the e-invoice schema (schema v2.0)
2. Upload to IRP via API call or direct portal (einvoice1.gst.gov.in). Multiple IRPs: NIC, Tata Consultancy, Clear, etc.
3. IRP validates the invoice: GSTIN verification, duplicate check (same GSTIN+FY+invoice number)
4. IRP generates IRN (64-character hash) and digitally signs the invoice JSON
5. IRP returns: signed JSON + IRN + QR code
6. Print QR code on the physical invoice and share with buyer
7. IRP auto-populates the invoice data to GSTR-1/GSTR-2A within 24 hours

Mandatory Invoice Fields for E-Invoice

• Supplier GSTIN, supplier name, supplier address, supply type (B2B/EXPWP etc.)
• Document type (INV/CRN/DBN)
• IRN (post-generation)
• Item details: HSN code (6/8 digit), quantity, unit, taxable value, GST rates, total
• Dispatch-to address, ship-to address (if different)
• E-way bill details (if goods — Part A auto-generated from e-invoice)

Integration of E-Way Bill with E-Invoice

From October 2020, if an e-invoice is generated for goods worth more than Rs.50,000, Part A of the e-way bill (EWB) is automatically populated from the e-invoice data. The transporter still needs to fill Part B (vehicle number) when transport commences. This eliminates duplicate data entry.

Consequences of Non-Compliance

• Invoice is invalid — buyer cannot claim ITC
• Invoice does not auto-populate in GSTR-2B — ITC leakage for buyer
• Penalty under Section 122: Rs.10,000 per invoice or tax amount (whichever is higher)
• Interest on ITC reversed by buyer

Key Practical Tips

• Cancel e-invoice within 24 hours for errors; after that issue credit/debit note
• Buyer should verify IRN on IRP portal before claiming ITC (scan QR code)
• Get API integration with IRP set up in your ERP before the threshold hits — avoid manual portal upload for high-volume businesses
• Archive e-invoice JSON files (signed) for 6 years as GST records