E-Invoice under GST

E-Invoice under GST

From 1 August 2023, every GST-registered business whose aggregate annual turnover (AATO) has crossed Rs. 5 crore in any financial year from FY 2017-18 onwards must authenticate all B2B tax invoices, credit notes and debit notes on the Invoice Registration Portal (IRP) before issuing them to the buyer. The authenticated document carries a unique Invoice Reference Number (IRN) and a digitally signed QR code. Without these, the invoice is legally void for ITC purposes — no IRN means no input tax credit for your buyer, and a per-invoice penalty exposure under Section 122 of the CGST Act 2017 for you.

What E-Invoicing Actually Is (and What It Is Not)

A common misconception is that e-invoicing means logging into a government portal and creating invoices there. That is wrong, and it matters operationally.

An e-invoice is a standard tax invoice that you generate inside your own ERP, accounting software or billing system. The difference is that the invoice data must conform to a government-mandated JSON schema called INV-01 before it is transmitted to the IRP. The IRP then:

1. Validates the JSON structure and the supplier's GSTIN against the GST portal records
2. Checks for duplicate IRN generation (same Supplier GSTIN + Financial Year + Document Type + Document Number combination)
3. Assigns a unique 64-character Invoice Reference Number (IRN) — a SHA-256 hash derived from the above four parameters
4. Generates a digitally signed QR code embedding the IRN, invoice value, tax amounts, buyer GSTIN and HSN
5. Returns the signed JSON to you, typically within 1–3 seconds for API calls

The returned, authenticated invoice — carrying the IRN and QR code — is what you print or share electronically with your buyer. The buyer's accounts payable team or ERP can scan the QR code to independently verify authenticity without calling anyone.

Critically, the IRP also pushes the invoice data in real time to:

• GSTR-1, auto-populating the relevant tables (Table 4A for B2B supplies, Table 6A for exports, Table 9B for credit/debit notes)
• The e-way bill portal, pre-filling Part-A of EWB-01

This dual push is why e-invoicing is not just a compliance tick-box — it eliminates parallel data entry in GSTR-1 and the e-way bill system, two tasks that historically consumed significant staff time every month.

Who Must Comply: Applicability and Thresholds in FY 2026-27

The CBIC has progressively tightened the turnover threshold since the system launched in October 2020:

The critical rule for FY 2026-27: If your AATO exceeded Rs. 5 crore in any financial year from 2017-18 to the present, you are inside the e-invoicing net — permanently. The trigger is historical, not current-year revenue. A business that peaked at Rs. 7 crore in FY 2022-23 and fell back to Rs. 3 crore in FY 2025-26 still must generate IRNs in FY 2026-27. There is no provision to exit the system based on reduced turnover.

The e-invoicing obligation applies to:

• B2B supplies — taxable, nil-rated and exempt, where a tax invoice is issued to a registered buyer
• Exports — with or without payment of IGST
• Supplies to SEZ units and SEZ developers
• Credit notes and debit notes linked to any of the above supply types

B2C invoices (supplies to unregistered buyers) do not require IRN. However, a separate Dynamic QR Code mandate applies to B2C invoices above Rs. 500 for taxpayers with AATO above Rs. 500 crore — this is governed by Notification No. 14/2020-CT and is distinct from IRN generation.

Who Is Exempt: The Eight Carve-Outs

Even if your turnover crosses Rs. 5 crore, e-invoicing does not apply to the following categories as notified under Notification No. 13/2020-CT and its amendments:

1. SEZ units — SEZ developers must comply; SEZ units manufacturing within the zone are excluded
2. Banking companies and financial institutions regulated by RBI
3. Non-Banking Financial Companies (NBFCs)
4. Insurance companies regulated by IRDAI
5. Goods Transport Agencies (GTAs) for the purpose of issuing consignment notes for road transport of goods
6. Passenger transportation service providers
7. Multiplex cinema operators for admission tickets issued to audiences
8. Government departments and local authorities

These exemptions apply to the category of supply or entity type, not to all activities of the entity. A large NBFC that also leases commercial office space and issues tax invoices to tenants should obtain specific legal advice on whether those invoices require IRN. The safe approach is to confirm applicability transaction-type by transaction-type rather than assume blanket exemption.

The IRN Generation Process: Step by Step

Here is a practical sequence you can hand directly to your accounts or ERP team:

Step 1 — Clean your master data first Verify that every customer's GSTIN, legal name, PIN code and HSN/SAC codes are correct in your system. The IRP hard-rejects JSON with a supplier GSTIN that is inactive or cancelled. It also checks the buyer GSTIN format. Incorrect data means a failed API call and a blocked invoice. Run a GSTIN validation batch against the GST portal search before going live.

Step 2 — Generate the invoice in your system using INV-01 schema Create the invoice as usual. Your accounting software or ERP must output data in the GSTN-mandated INV-01 JSON format. Tally Prime, Zoho Books, Busy Accounting, MARG ERP, and major SAP/Oracle implementations have built-in e-invoice modules. If your system does not natively support the schema, a GSP/ASP middleware layer converts your invoice data before transmission.

Step 3 — Transmit JSON to the IRP You have three channels, and the right choice depends on volume:

• Direct API — fastest, suitable for 500+ invoices per month, requires technical integration and sandbox testing
• GSP/ASP middleware — the GSP handles API connectivity, retry logic and error handling; reliable for mid-volume businesses
• Bulk upload utility — upload a JSON or CSV batch file directly on the IRP portal; suitable for fewer than 500 invoices per month

As of FY 2026-27, there are multiple accredited IRPs beyond NIC: ClearTax IRP, IRIS Business Services IRP, EY IRP, Deloitte IRP and others. Any accredited IRP generates the same standardised IRN. Your choice of IRP does not affect the IRN validity.

Step 4 — Receive and store the authenticated response The IRP returns a signed JSON containing the Irn (64-character hash), AckNo (acknowledgement number), AckDt (acknowledgement date/time), SignedQRCode and SignedInvoice. Log all four fields in your internal IRN register against the invoice number.

Step 5 — Print and share only the authenticated invoice Configure your ERP to release the invoice PDF only after the IRP response is received and the IRN is embedded. The physical or digital invoice shared with your buyer must display: the IRN, the QR code and the acknowledgement date. A buyer who receives an invoice without these elements has valid grounds to withhold payment pending a valid re-issue.

Step 6 — Reconcile your IRN log monthly Compare your internal IRN log with the auto-populated entries in GSTR-1 and flag any invoice number that has an IRN in your system but does not appear in GSTR-1. These mismatches — usually caused by wrong buyer GSTINs or portal sync delays — must be corrected before GSTR-1 is submitted.

Time limit for IRN generation: CBIC has notified a restriction on back-dated IRN generation. As of the date of this post, this time-window restriction is active for taxpayers with AATO above Rs. 100 crore. Verify the current notification applicable to your AATO band before assuming that IRNs can be generated for invoices of any age — the window may be extended to lower thresholds during FY 2026-27.

Auto-Population of GSTR-1 and E-Way Bill: What Really Happens

GSTR-1 auto-population: Once the IRP authenticates an invoice, the data flows to GSTR-2B for the buyer and auto-populates GSTR-1 in the supplier's portal — typically within 24 hours. You still need to review and submit GSTR-1 by the due date: the 11th of the following month for monthly filers, or the 13th of the month following the quarter for QRMP scheme filers. Auto-population is not auto-filing. Missing the GSTR-1 due date still attracts a late fee of Rs. 50 per day (Rs. 25 CGST + Rs. 25 SGST), capped at Rs. 10,000 per return period.

E-way bill auto-generation: If transporter details and approximate distance are included in the invoice JSON, an e-way bill is generated automatically for the consignment — no separate EWB-01 filing needed. If transporter details are not available at invoice time (common when the logistics booking happens after invoicing), Part-A of EWB-01 is auto-populated and either the supplier or transporter completes Part-B (vehicle number) before goods move.

Practical timing alert: Generate the IRN at the time of dispatch preparation, not hours earlier. If you generate an IRN at 9 AM, the goods move at 3 PM, but you realise at 2 PM that the invoice value was wrong — you have missed the 24-hour cancellation window only if you generated the IRN more than 24 hours ago. But if the goods have already moved with an e-way bill linked to that IRN, cancelling the IRN after the fact creates an EWB-IRN mismatch that will be flagged at checkpoints. Sequence matters: fix errors before the truck leaves.

Worked Example: The Cost of a 45-Day Blind Spot

Scenario: Precision Parts Pvt. Ltd., a Pune-based auto-components manufacturer, recorded Rs. 6.2 crore AATO in FY 2023-24, crossing the Rs. 5 crore threshold. From 1 August 2023, they were inside the e-invoicing net.

What went wrong: Their accounts team continued raising invoices from Tally without enabling the e-invoice module. Over 45 days (August–mid-September 2023), they raised 420 B2B invoices without IRN.

Invoice economics:

• Average invoice value: Rs. 85,000 (excluding GST)
• Average GST at 18%: Rs. 15,300 per invoice
• Total tax across 420 invoices: Rs. 64,26,000

Penalty exposure under Section 122(1)(a) of the CGST Act 2017:

> Penalty = higher of Rs. 10,000 or the tax evaded per invoice

Since Rs. 15,300 > Rs. 10,000, the applicable penalty is Rs. 15,300 per invoice.

Total penalty exposure: 420 × Rs. 15,300 = Rs. 64,26,000

Additionally, all 420 buyers received invoices that did not appear in their GSTR-2B (because no IRN was generated, no data was pushed to GSTR-1). Buyers began withholding payments, raised disputes and started returning goods citing "invalid documentation."

The remediation cost:

• Credit notes issued against 420 invoices → reissued with IRN: 3 working days of accounts staff time
• Voluntary disclosure filed with the jurisdictional GST officer
• Compounded penalty negotiated; tax for disputed period paid with interest
• Two large buyers placed the supplier on a 90-day payment hold pending "system verification"

What 30 days of preparation would have cost: Zero. Enable the e-invoice module in Tally Prime, run five test invoices in the IRP sandbox, train two people, done.

Common Mistakes and How to Fix Them

IRN generated after invoice shared with buyer

Problem: The PDF goes to the buyer first; the IRN is generated afterwards and a new PDF is sent. The buyer has filed the original (invalid) invoice number in their purchase register. When GSTR-2B populates, there may be a timing mismatch.

Fix: Hard-lock your ERP so that the PDF generation step is only triggered after the IRP response is stored. If your software does not support this natively, create a manual SOP: IRN first, invoice release second — no exceptions.

Cancelling an IRN after 24 hours

Problem: An IRN can only be cancelled on the IRP within 24 hours of generation. After that, the IRP will not accept a cancellation request.

Fix: A same-day or early-morning review of the previous day's IRNs catches errors in time. Errors discovered after 24 hours must be reversed with a credit note (for overcharges or cancellations) or a supplementary invoice (for undercharges). Both the credit/debit note and the correcting invoice also require IRN.

Wrong buyer GSTIN

Problem: A buyer has multiple GSTINs (one per state). An invoice is raised against the Delhi GSTIN but the goods are dispatched from and delivered to the Mumbai branch. The ITC accrues at the wrong GSTIN, creating a mismatch for the buyer.

Fix: Confirm the billing GSTIN with the buyer at order stage. Maintain a ship-to/bill-to distinction in your ERP and populate both in the INV-01 JSON (the schema supports BuyerDtls and DispDtls as separate nodes).

Missing 8-digit HSN codes

Problem: For taxpayers with AATO above Rs. 5 crore, tax invoices must carry 8-digit HSN codes. A 4-digit HSN may pass IRP validation but will trigger scrutiny in GSTR-9C reconciliation and GST audit.

Fix: Audit your HSN/SAC master at the start of each financial year. Map every product and service to its correct 8-digit HSN, cross-reference the GST rate schedule and update your ERP before the April invoicing cycle begins.

Treating IRP auto-population as GSTR-1 submission

Problem: Because the IRP pushes data to GSTR-1 automatically, some businesses assume the return is filed. GSTR-1 is auto-populated, not auto-submitted. An unfiled GSTR-1 means the buyer cannot see confirmed ITC in GSTR-2B, and the supplier incurs late fees.

Fix: Set a calendar reminder for the 10th of every month (to review) and the 11th (to submit). For QRMP filers, the deadline is the 13th of the month following the quarter. Treat GSTR-1 submission as a separate, mandatory monthly step regardless of how clean the auto-population looks.

Choosing Your IRP Integration Model

Your integration method should match invoice volume, ERP maturity and IT capacity:

Direct API — High-volume taxpayers (5,000+ invoices/month) Register directly with an accredited IRP and build API connectivity from your ERP. This requires sandbox testing (all accredited IRPs provide a test environment), technical development time and ongoing maintenance. The per-invoice cost is lowest at scale, and response times are fastest. Have a fallback — download and configure the GSTN offline utility so that a brief IRP downtime does not halt your dispatch schedule.

GSP/ASP Integration — Mid-volume taxpayers (500–5,000 invoices/month) A GST Suvidha Provider (GSP) or Application Service Provider (ASP) acts as certified middleware. The GSP handles API authentication, error retries and schema validation. Tally Prime, Busy and most mid-market accounting systems have built-in GSP connectivity — enable the e-invoice module, configure your GSTIN credentials and the GSP does the rest. SLA-backed uptime and error alerts make this the right choice for most manufacturing, trading and services businesses.

Bulk Upload Utility — Low-volume taxpayers (fewer than 500 invoices/month) Available directly on IRP portals. Prepare invoices in the downloadable Excel/JSON template, upload the batch, download authenticated responses. Operationally slower but perfectly adequate for professional services firms, consultants and distributors with low invoice frequency.

Monthly IRN reconciliation — all categories: Regardless of integration model, run a monthly three-way reconciliation: your IRN log vs. GSTR-1 auto-populated data vs. your books of account. Any invoice that appears in two of the three but not the third is a compliance gap. Catching these in month M+1 is manageable; catching them in a GST audit two years later is expensive.

Penalties for Non-Compliance: The Numbers

Non-compliance with e-invoicing is treated as issuing an invalid tax invoice under the CGST Act 2017:

• Section 122(1)(a): Rs. 10,000 per invoice or the tax amount on that invoice, whichever is higher
• Section 16(2)(aa): Buyer's ITC is disallowed where the invoice does not reflect in GSTR-2B — which it will not, without an IRN
• Section 129: Goods moving without a valid e-way bill (which would have auto-generated from the IRN) are liable to detention; penalty is 200% of the applicable tax on the detained goods

There is no statutory "first offence" exemption for e-invoicing lapses. Adjudicating officers may consider voluntary disclosure and prompt tax payment in mitigation, but the ITC impact on your buyers is immediate and not reducible by post-hoc penalty negotiations.

Key Takeaways

• The threshold is historical, not current-year: If your AATO exceeded Rs. 5 crore in any year from FY 2017-18 onwards, you must generate IRNs in FY 2026-27, even if current revenue is lower. There is no exit provision.
• No IRN = invalid invoice: An invoice without an IRN is legally unenforceable for ITC purposes. Your buyer bears ITC denial risk; you bear the per-invoice penalty risk under Section 122(1)(a).
• Cancel within 24 hours or use a credit note: The IRP cancellation window is hard-capped at 24 hours from generation. Beyond that, a credit note is the only remedy — and the credit note itself requires an IRN.
• Auto-population ≠ auto-filing: GSTR-1 must still be reviewed and submitted by the 11th (monthly filers) or 13th (QRMP filers). Missed filing attracts late fees of Rs. 50 per day.
• The e-way bill auto-generates when transporter details are in the JSON — but goods must not move until Part-B (vehicle number) is also complete. Sequence: IRN → EWB with Part-B → dispatch.
• Penalty arithmetic is per invoice: At a minimum of Rs. 10,000 per un-authenticated invoice, 100 missed invoices at a mid-sized business equals a Rs. 10 lakh floor exposure — before ITC loss for buyers.
• Onboard 30 days early: Test in the IRP sandbox, validate your GSTIN master, enable the e-invoice module, run mock invoices and train two staff members — all before your compliance date or before the next threshold reduction takes effect.