e-Invoice under GST (India, FY 2026-27)

1. What an e-Invoice actually is

An e-Invoice under GST is a tax invoice that has been reported to and validated by the Invoice Registration Portal (IRP) at the time of issue. The IRP returns two artefacts that become permanent parts of the invoice — the IRN (Invoice Reference Number, a 64-character SHA-256 hash) and a digitally signed QR code.

It is not, despite the name, a special type of invoice or a different format. The underlying invoice is your usual tax invoice under Rule 46 of the CGST Rules and Section 31 of the CGST Act. What changes is that before it leaves your system, it gets registered with the Government's portal so that the recipient's ITC, your GSTR-1, and the e-Way bill all reference the same immutable record. For the broader GST framework this sits inside — registration thresholds, returns, ITC rules — see our GST guide.

What the IRN gives you

• Auto-population of GSTR-1 outward-supplies table
• Auto-population of buyer's GSTR-2B (and therefore ITC eligibility)
• Auto-population of e-Way bill Part-A (skip retyping invoice details)
• Tamper-proof proof of issue date for tax-period determination
• A QR code that any field officer can scan to verify authenticity

2. e-Invoice turnover limit — who must generate

The e-Invoice turnover limit for FY 2026-27 is ₹5 crore. Any registered taxpayer whose aggregate annual turnover (AATO) crossed ₹5 crore in any financial year since 2017-18 must generate e-Invoices for B2B supplies, exports and SEZ supplies. The trigger is historic — once you cross the threshold in any FY, the mandate applies permanently, even if turnover later drops.

Threshold rollout timeline

Which transactions need an IRN

• B2B tax invoices — supplies to a registered person
• Supplies to SEZ — with or without payment of IGST
• Exports — with or without payment of IGST
• Deemed exports — supplies to EOU / advance authorisation holders
• Credit notes and debit notes against any of the above

B2C invoices, delivery challans, job-work challans, bill of supply (composition / exempt) and self-invoices for purchases from unregistered persons are out of scope.

3. The IRPs — NIC and the four private

GSTN has authorised six Invoice Registration Portals. They share the same schema, the same validation rules, and the same backend GSTN repository — so the IRN generated by any one is equally valid.

NIC IRPs are the default — most taxpayers and accounting software register there. The private IRPs add value via better API uptime, dashboards and bulk-cancellation tooling. You can switch IRPs at will; the registered IRN belongs to GSTN, not to the IRP.

4. The INV-01 schema — mandatory and optional fields

The e-Invoice payload follows the INV-01 JSON schema published by GSTN. The schema has six primary sections.

• TranDtls — transaction type (B2B, SEZWP, SEZWOP, EXPWP, EXPWOP, DEXP), tax scheme (GST), supply type, RCM indicator.
• DocDtls — document type (INV, CRN, DBN), document number (alphanumeric, max 16 chars), document date.
• SellerDtls — supplier GSTIN, legal name, trade name, address, state code, pincode, phone, email.
• BuyerDtls — recipient GSTIN, legal name, address, state code, place of supply.
• ItemList — line-by-line — HSN code, item description, quantity, unit, unit price, taxable value, GST rate (CGST + SGST or IGST), cess rate, total item-level tax.
• ValDtls — invoice-level totals — taxable value, total CGST / SGST / IGST / Cess, total invoice value, round-off, other charges.

Optional sections cover dispatch-from address, ship-to address (third-party doctrine), e-Way bill details, payment terms, reference documents, and additional information.

5. The 30-day reporting rule (AATO ≥ ₹10 crore)

With effect from 1 April 2025, taxpayers with aggregate annual turnover of ₹10 crore or more must report each invoice to the IRP within 30 days of its document date. The IRP rejects submissions after the 30-day window — there is no override.

Why this matters operationally: back-dated invoicing is no longer possible at this band. If month-end closing crosses into the next month, you cannot raise a 31-March invoice on 10-May and expect it to register. Either you raise it on 10-May with a May date, or you don't raise it at all.

Field implications

• Sales returns / disputes: a credit note issued more than 30 days after the original is fine (credit note has its own 30-day clock from its own date).
• Continuous supply of services: the invoice date is the earlier of the statement date or payment date — keep statements current.
• Year-end accruals: if you tend to book March invoices in April, this no longer works at AATO ≥ ₹10 crore.

6. The IRN generation workflow — how is an IRN generated?

Whether you use the web portal, the IRP API, or your accounting software's integration, the underlying workflow is the same.

1. Capture the sale in your books with all schema-required fields populated.
2. Generate the INV-01 JSON — your software builds the structured payload.
3. Authenticate to the chosen IRP — API key, GSTIN, time-bound auth token.
4. POST the JSON to the /eivital/v1.04/Invoice endpoint.
5. Receive response — on success, the IRP returns the IRN, the signed QR code (Base64), the AckNo and AckDt. On failure, it returns an error code (e.g., 2150 — duplicate, 2172 — buyer GSTIN inactive).
6. Print on invoice — the IRN and QR are rendered on the physical / PDF invoice as required by Rule 48(4).
7. Issue to buyer — the invoice with IRN and QR is what gets sent.

Round trip is typically under 2 seconds. The IRP signs the QR code with its private key — buyers and field officers can verify the signature against GSTN's public key.

7. Cancellation within 24 hours — how to cancel an e-Invoice?

An IRN can be cancelled on the IRP within 24 hours of generation. After 24 hours, the IRN is locked for life — the only correction route is a credit note.

What you cannot cancel

• An IRN where the e-Way bill has been generated and goods have moved
• An IRN cancelled once — cannot reverse the cancellation
• An IRN beyond 24 hours — credit-note route only

Cancellation reason codes

• 1 — Duplicate
• 2 — Data entry mistake
• 3 — Order cancelled by buyer
• 4 — Others (specify)

Once cancelled, the document number on the cancelled IRN cannot be reused for a fresh IRN in the same FY. Choose a different document number for the corrected invoice.

8. Credit notes and debit notes — do they need an IRN?

Credit notes (document type CRN) and debit notes (DBN) issued by an e-Invoice-mandated taxpayer must carry an IRN. The schema is identical to the invoice schema, plus a PrecDocDtls block linking back to the original invoice number and date.

Time limits

• Credit note reducing tax must be issued by 30th November of the FY following the supply (linked to the Section 34(2) deadline for filing the credit note in returns).
• Debit note has no outer time limit — but the recipient's ITC on the debit note is bound by Section 16(4): claim by 30th November of the FY after the debit note's FY.
• If AATO ≥ ₹10 crore: the 30-day rule applies to credit and debit notes too — from the note's own date, not from the original invoice.

9. e-Invoice vs e-Way bill — the interlock

e-Invoice and e-Way bill are two separate compliances that share a data backbone. From late 2020 onwards, when you generate an IRN, you can simultaneously generate the e-Way bill in the same API call — the IRP carries the payload across to the e-Way bill portal.

How they relate

• Part-A of the e-Way bill (invoice details, consignor, consignee, item-level GST) is identical to the e-Invoice payload — it auto-populates from the IRN.
• Part-B (vehicle number, mode, transporter) must still be added separately — the IRP doesn't know the vehicle.
• If the IRN is cancelled, the linked e-Way bill is also auto-cancelled.
• For consignments over ₹50,000, both are required (or only e-Way bill if you are below the e-Invoice threshold).

For the full e-Way bill rules — validity, state thresholds, Part-B updates — see our e-Way Bill guide.

10. Bulk e-Invoice generation

For ERP-driven invoice volumes, the IRP exposes a bulk endpoint accepting up to 1,000 INV-01 records per request. The response is line-by-line — each record returns either an IRN+QR or an error code.

Patterns that work in production

• Batch in 100-200 line groups rather than pushing 1,000 — faster recovery from transient errors.
• Idempotency: the IRP rejects duplicates via document-number hashing. Your retry logic must be safe — re-posting the same record gets the same IRN back.
• Failure isolation: one bad line doesn't fail the batch. Pull failed records into a repair queue and re-submit.
• Throttle on auth tokens: NIC IRP tokens are valid for 6 hours; refresh proactively rather than on expiry.

11. Practical mistakes that break IRN submissions

• Wrong recipient GSTIN. The IRP validates the GSTIN against GSTN's active-registration database. Cancelled or inactive GSTINs fail with error 2172. Always use a real-time GSTIN-validation API in your billing screen.
• HSN code mismatch with rate. The IRP runs sanity checks — claiming 5% GST on an HSN that is normally 18% raises warnings and may reject. Maintain a clean HSN-master with rates.
• State code in address vs place of supply. If supplier state and place-of-supply don't match, you cannot charge CGST+SGST. Conversely, intra-state with IGST is rejected. Common when invoicing between branches.
• Document number reuse. Same invoice number used twice in the same FY — even across different series — is rejected.
• B2C invoice sent to IRP. Wasted call. Filter at the source — only B2B and SEZ / export transactions go to the IRP.
• RCM invoice flag wrong. The RCM indicator must be set to Yes for inward-leg invoices the recipient self-invoices. Get this wrong and the recipient cannot claim the RCM credit cleanly.
• Decimal precision drift. Item-level tax must round to two decimal places; invoice-level totals must reconcile. A 1-paisa drift across 50 lines is enough to fail the ValDtls reconciliation check.

12. What happens to invoices missing IRN — buyer's ITC blocked

An invoice from an e-Invoice-mandated supplier that does not carry an IRN is treated as not a valid tax invoice under Rule 48(5). The consequences:

• The supplier's GSTR-1 auto-population doesn't include the invoice.
• The buyer's GSTR-2B doesn't reflect the invoice.
• Buyer's ITC is blocked under Section 16(2)(aa) — the invoice must appear in 2B.
• Supplier may face penalty under Section 122 — ₹10,000 or 100% of tax, whichever is higher, per missed invoice.

Buyers increasingly check the QR code at receipt — if there isn't one, they reject the invoice and ask for a re-issue. Treat IRN as a hard prerequisite of any tax invoice you issue once you cross ₹5 crore.

13. Exemptions from e-Invoice — who is exempt?

Notification 13/2020-CT (as amended) exempts the following by class of taxpayer:

• Insurer or banking company or financial institution including NBFC
• Goods Transport Agency (GTA) supplying transportation services by road
• Passenger transportation service providers
• Multiplex cinema admission services
• Government departments and local authorities
• SEZ units (but NOT SEZ developers — they are covered)
• Persons supplying through an e-commerce operator under Section 9(5)

Exemption is by entity type, not by transaction. A bank that also has a separate non-banking line of business still doesn't need to generate IRNs for its bank invoices — the entity is exempt. For an exempt supplier's buyer, ITC is not blocked by Rule 48(5); GSTR-1 / 2B continue to flow without IRN.

14. e-Invoice for exports

Exports are covered by the e-Invoice mandate. The schema has two dedicated transaction types:

• EXPWP — Export with payment of IGST. Refund of IGST is claimed by the exporter later.
• EXPWOP — Export without payment of IGST, under LUT (Letter of Undertaking, Form RFD-11). Refund of accumulated ITC is claimed instead.

The IRN-generated invoice flows to ICEGATE (Customs) when the shipping bill is filed. Match of GSTR-1 + shipping bill + BRC (bank realisation certificate) is the three-pillar refund test — the IRN keeps the GSTR-1 leg tight.

SEZ supplies

SEZ supplies have dedicated transaction types: SEZWP (with payment) and SEZWOP (without payment). SEZ units are exempt from generating IRNs themselves; suppliers to SEZ units are not.

15. Tools and IRP integration

Three integration models cover most taxpayers:

• Direct API integration from accounting software. Your accounting tool (TatvaBooks, Zoho Books, Tally with e-Invoice add-on, QuickBooks India) posts to the IRP API at the moment the invoice is saved. IRN and QR are automatic. This is the cleanest model — no separate upload step.
• Excel upload via NIC portal. For lower volumes (under 100 invoices a month) without an integrated tool. Generate INV-01 JSON manually from an Excel template, upload, download IRN, paste back into your invoice. Tedious and error-prone — fine as a fallback.
• GSP-based ERP integration. For SAP / Oracle / Microsoft Dynamics shops. A GST Suvidha Provider (GSP) sits between the ERP and the IRP, mapping ERP invoice formats to INV-01 and handling auth-token rotation.

TatvaBooks prepares the e-Invoice for you. Every sale voucher above your e-Invoice threshold builds the INV-01 payload and places the IRN + QR on the invoice PDF — no separate JSON upload to wrangle. Live filing to the NIC portal is on our near-term roadmap. See our migration guide for the switching process.

16. Frequently asked questions

17. e-Invoice glossary

IRN

Invoice Reference Number — 64-character SHA-256 hash issued by the IRP for every e-Invoice.

IRP

Invoice Registration Portal — six authorised portals (NIC1, NIC2 + four private) that register e-Invoices.

INV-01

GSTN-published JSON schema for the e-Invoice payload.

AATO

Aggregate Annual Turnover — PAN-India turnover used to decide the e-Invoice threshold.

QR code

Digitally signed CBOR-encoded payload returned by the IRP, printed on the invoice for verification.

Ack No / Ack Dt

Acknowledgement number and date returned by the IRP on successful submission.

CRN / DBN / INV

Document types — Credit note, Debit note, Invoice.

EXPWP / EXPWOP

Export with payment / without payment (under LUT).

SEZWP / SEZWOP

SEZ supply with / without payment of IGST.

LUT

Letter of Undertaking — Form RFD-11, lets exporters supply zero-rated without paying IGST. Renewed each FY.

GSP

GST Suvidha Provider — third-party intermediary connecting ERPs to the GST and IRP APIs.

NIC

National Informatics Centre — Government body operating the primary IRPs.

Rule 48(4)

CGST Rule mandating e-Invoice for prescribed classes of registered persons.

Rule 48(5)

CGST Rule providing that an invoice not registered via IRP is not a valid tax invoice.

Section 122

Penalty section — ₹10,000 or 100% of tax, whichever higher, per non-IRN invoice.