E-Invoicing Under GST: Complete Guide for 2026

What e-invoicing actually is

E-invoicing is the process of reporting B2B invoices to the government's Invoice Registration Portal (IRP) before they're issued to your customer. The IRP validates the invoice, assigns a unique Invoice Reference Number (IRN), and returns a digitally signed QR code that must appear on the final invoice. Without a valid IRN, a B2B invoice is not treated as valid for GST purposes.

Who needs to e-invoice

Applicability is based on aggregate turnover in any preceding financial year since GST rollout. The threshold has been progressively lowered over successive notifications and now covers most mid-sized businesses — well below the ₹5 crore mark. If you're unsure whether e-invoicing applies to you, a quick GST advisory & health check will confirm your exact applicability and flag any invoices you've missed.

How the workflow fits into GSTR-1

Once an invoice is registered on the IRP, its details auto-populate into your GST monthly return filing, cutting down duplicate data entry and mismatches. This is also why getting e-invoicing wrong — wrong IRN, invoice raised without one, or a cancelled invoice not synced — tends to show up later as return mismatches or blocked input tax credit for your buyer.

Common mistakes

The most frequent issues we see: generating the IRN after the invoice date instead of before, forgetting to cancel an e-invoice within the 24-hour window when an order falls through, and missing e-invoicing for debit/credit notes, which are covered by the same rule as invoices.

FAQs

Does e-invoicing apply to B2C sales? No — e-invoicing currently applies only to B2B, SEZ and export supplies, not to retail B2C bills.

Can an e-invoice be cancelled? Yes, within 24 hours of IRN generation on the IRP. After that, you'll need to issue a credit note instead.