TL;DR
- Threshold in 2026: ₹3 crore turnover (any of last 3 financial years).
- Applies to B2B invoices, credit notes, debit notes, exports. B2C is exempt.
- You generate the IRN (Invoice Reference Number) via the IRP (Invoice Registration Portal) before raising the invoice.
- Most accounting software (Tally / Zoho / Vyapar) does this automatically; custom systems need a GSP/ASP integration.
What e-invoicing actually means
Before raising a B2B invoice, you submit the invoice JSON to the IRP, which validates it and returns:
- IRN — a 64-character hash unique to that invoice
- QR code — embeds key invoice fields (GSTIN, date, value, IRN)
- Acknowledgement number + date
You print the QR + IRN on the invoice you send to your buyer. The IRP also auto-pushes the data to GSTR-1 (your sales return) and the e-way bill system. Big win — no double entry.
Who's covered in 2026
| Turnover (any of last 3 FY) | e-Invoicing required? |
|---|---|
| <₹3 crore | No (voluntary) |
| ≥₹3 crore | Yes — for B2B invoices |
| SEZ developers / units, banks, insurance, GTA, passenger transport | Exempt regardless |
The integration options for your business
Option 1 — Use accounting software that handles it
Tally Prime, Zoho Books, Vyapar, ClearTax, Marg — all have built-in e-invoicing. Your team raises invoices in the software; software auto-generates IRN + QR; you download the PDF.
Cost: ₹0 incremental (already paying for the software).
Effort: Enable e-invoicing in settings + register your GSTIN with the IRP. ~2 hours one-time.
Best for: SMEs without custom billing systems. Default choice.
Option 2 — Custom system + GSP/ASP integration
If you're billing through a custom CRM / ERP / SaaS app, you integrate with a GSP (GST Suvidha Provider) like ClearTax, IRIS, Cygnet, Masters India.
Cost: ₹5K–₹25K/month based on volume + ₹50K–₹2L for integration build.
Effort: 1–2 weeks dev work.
Best for: SaaS, marketplaces, or any business with custom billing engines.
Option 3 — Direct IRP API (DIY)
Technically possible. NPCI exposes the IRP API. You build your own integration without a GSP.
Cost: Free (no GSP fee). High dev cost.
Effort: 3–4 weeks (auth, retry logic, rate limit handling, error codes are poorly documented).
Only worth it if you're high-volume (50K+ invoices/month) or building a billing platform yourself.
What changes for your buyer
Your B2B buyer can verify the IRN on the GSTN portal. The invoice you send must have the QR code visible (printed PDF, email PDF, or web view). Without IRN/QR, the buyer's auditor will flag it as non-compliant — and your buyer may delay payment.
Common mistakes
- Generating IRN after raising the invoice: wrong. IRN is required BEFORE you issue. Backdating doesn't work; the IRP rejects.
- Missing the 24-hour amendment window: invoices can only be cancelled (not amended) on IRP, and only within 24 hours. After that, raise a credit note.
- Ignoring B2C QR for ₹500 crore+ businesses: separate rule — B2C QR is mandatory for businesses >₹500 cr turnover. Most SMEs don't hit this.
- Mismatched GSTIN in invoice and on IRP: causes IRP rejection. Always validate buyer's GSTIN before raising.
For our SME and SaaS clients above the ₹3 cr threshold, we typically integrate the ClearTax or IRIS GSP API into their billing flow. End-to-end: customer pays → invoice raised → IRN generated → PDF emailed with QR → posted to Tally — all automated. See SME automation builds →
FAQ
What about the ₹50K rural exemption?
Rumour. There's no rural exemption for e-invoicing. Threshold is purely turnover-based.
If I'm under threshold, should I voluntarily comply?
Probably not. Adds operational complexity for no compliance upside. Wait until you cross ₹3 cr.
What if the IRP is down when I need to raise an invoice?
IRP downtime is rare but happens. You can raise the invoice without IRN as a "draft" and submit later — but legally, the IRN-less invoice isn't valid for ITC. Most ERPs queue and retry automatically.
Last reviewed: 18 April 2026 · Threshold and IRP rules per CBIC notifications current as of April 2026.
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