What is GST E-Invoicing in India?

GST e-invoicing, defined

GST e-invoicing is not a separate invoicing system — it is a verification layer on top of your existing invoicing. Every B2B invoice you raise in India (above the turnover threshold) must be sent in real time to the government's Invoice Registration Portal (IRP), which assigns an Invoice Reference Number (IRN) and a QR code. These must be printed on the physical or PDF invoice for the buyer to claim Input Tax Credit (ITC).

What an IRN actually looks like

An IRN is not a random number. It is a SHA-256–derived 64-character hex string computed by the IRP from four pieces of your invoice: the supplier GSTIN, the financial-year code, the document-type tag (INV, CRN, or DBN), and the document number. Same four inputs always produce the same IRN — that deterministic mapping is what stops the same invoice being submitted twice.

What lives inside that hex (provable on demand, not visible in the string):

• Supplier GSTIN — must be active and registered for e-invoicing on the GSTN portal.
• Financial year — six-character form like 2025-26; must fall within ±1 of the invoice date.
• Document type — INV for tax invoice, CRN for credit note, DBN for debit note.
• Document number — your internal invoice number; must be unique within the (GSTIN, FY, DocType) combination.

The IRP rejects the submission instantly if any of these mismatch. That's why "the IRP wouldn't accept it" is almost always a master-data problem — wrong GSTIN, duplicate document number, wrong financial year on the invoice header — not a network issue.

Threshold history — why everyone is in scope now

The GST e-invoicing turnover threshold has only ever moved in one direction:

• 2020 — ₹500 Cr turnover threshold
• 2021 — ₹100 Cr
• 2022 — ₹20 Cr
• 2023 — ₹10 Cr
• 2024 — ₹5 Cr
• 2026 — ₹5 Cr (current)

Trajectory suggests the threshold will continue to drop. Any B2B distribution company above ₹3 Cr turnover should assume e-invoicing applies to them within 12–18 months and start preparing now.

How e-invoicing works end-to-end

1. Distributor raises a B2B invoice in their DMS / ERP.
2. The DMS submits the invoice to the IRP via API (or via a GSP — GST Suvidha Provider).
3. The IRP validates GSTIN, HSN codes, GST rates, and other fields.
4. If valid, IRP returns IRN + QR code. If invalid, IRP returns an error code; the distributor must fix data and re-submit.
5. The DMS embeds IRN and QR code on the invoice PDF and prints/emails to the buyer.
6. Accounting system syncs — the IRN, QR, and invoice all flow to Tally / SAP for ledger and audit trail.

All six steps must work for compliance. Any break — wrong HSN, stale GSTIN, missing QR on the printed invoice — creates a buyer ITC claim failure and a potential GST notice.

Common failure modes

• Stale buyer GSTIN. Buyer's GSTIN was active when set up but later suspended. Master data hygiene is non-negotiable.
• Wrong HSN code. Mixed-category distributors (FMCG + dairy + ancillary) often have HSN coverage gaps in the product master.
• Item-level GST rate mismatch. 5% vs 12% vs 18% rate errors propagate from product master imports.
• The 24-hour cancellation window. Sales teams try to "fix" old invoices by editing them, which is non-compliant. Credit notes are the correct path.
• Missing e-invoicing of credit notes. Original invoice e-invoiced; credit note skipped. Buyer ITC mismatches result.
• QR code not rendered on invoice template. IRN exists, but the printed invoice doesn't show the QR. Common ERP misconfiguration.

How AccountBook handles e-invoicing

AccountBook is Sort String's MIS-grade finance product. It handles e-invoicing end-to-end inside the same screen where the invoice is raised: IRP API submission via a licensed GSP, IRN capture, QR-code rendering on the printed/PDF invoice, automatic Tally Prime (XML) and SAP B1/HANA ledger sync, e-way bill generation for moves above ₹50,000, and the six-year audit-trail retention the GST rules require. Across 45 client companies we process more than 4.78 Lakh invoices a year with full IRN coverage.

For distribution businesses already on SalesPort, AccountBook plugs in alongside it so order capture, invoicing, IRN submission, payment collection and ledger posting all live on one customer record — no double entry, no manual GSTN portal upload, no Excel reconciliation.

For the operational deep-dive — the 14 points every distribution operations head should run through before the next GST cycle — read our GST e-invoicing readiness checklist.