A founder runs a services company that did ₹6.2 crore in FY 2022-23, then shrank to ₹3.8 crore in FY 2024-25 and ₹4.1 crore in FY 2025-26. His accountant tells him e-invoicing is not applicable — current turnover is below ₹5 crore. He keeps issuing ordinary tax invoices from his billing software. Eighteen months later a customer's GSTR-2B does not show the input tax credit, the customer withholds ₹9 lakh of payment, and the department issues a notice treating every one of those invoices as not a valid document under Rule 48(5).

The mistake is not arithmetic. It is a misreading of how the threshold is written. E-invoicing applicability is not a test of what you turned over last year. It is a permanent status you acquire the first time you cross the line — and you do not lose it by shrinking.

What the law actually requires

E-invoicing sits in Rule 48(4) of the CGST Rules 2017, inserted by Notification No. 68/2019-Central Tax and operationalised through a series of notifications that progressively lowered the turnover threshold. The current position, governed by Notification No. 10/2023-Central Tax dated 10 May 2023, is that e-invoicing is mandatory for every registered person whose aggregate annual turnover exceeded ₹5 crore in any financial year from FY 2017-18 onwards.

Read that phrasing carefully. It is "in any financial year from 2017-18 onwards" — not "in the preceding financial year." Once any single year since 2017-18 crossed ₹5 crore, the obligation attaches and remains attached. There is no de-registration mechanism, no fall-back provision, and no departmental process for exiting e-invoicing because turnover declined. As of FY 2026-27 the ₹5 crore threshold remains unchanged; proposals to lower it to ₹3 crore or ₹2 crore have been discussed but not notified.

Aggregate turnover is defined in Section 2(6) of the CGST Act 2017 and is wider than most founders assume. It is PAN-level, not GSTIN-level, and it includes taxable supplies, exempt supplies, exports, and inter-state supplies of persons having the same PAN, computed on an all-India basis. It excludes CGST, SGST, IGST, and cess. A company with three GSTINs across Karnataka, Maharashtra, and Telangana adds all three together. A company with substantial exempt or export revenue counts that revenue in full — many exporters wrongly assume zero-rated supplies sit outside the calculation. They do not.

What an e-invoice actually is

The most persistent misunderstanding is that an e-invoice is a document generated by the government portal. It is not. You continue to raise the invoice in your own accounting or ERP system. What changes is that before the invoice is issued to the buyer, its data must be reported in the notified INV-01 schema to an Invoice Registration Portal (IRP), which returns two things:

The IRN (Invoice Reference Number) — a 64-character hash generated from the supplier's GSTIN, the financial year, the document type, and the document number. It is the unique fingerprint that tells the GST system this invoice legally exists.

The signed QR code — containing the supplier GSTIN, recipient GSTIN, invoice number and date, invoice value, number of line items, the HSN code of the main item, and the IRN itself, all digitally signed by the IRP.

Rule 46(r) of the CGST Rules requires the QR code to be printed on the invoice issued to the buyer. Rule 48(5) is the provision that carries the sting: an invoice that was required to be issued under Rule 48(4) but was not so issued shall not be treated as an invoice at all. Not defective. Not irregular. Not an invoice.

What is covered and what is not

E-invoicing applies to B2B supplies, supplies to SEZ units and developers, exports (with or without payment of tax), and deemed exports. It also applies to credit notes and debit notes issued against those supplies.

It does not apply to B2C supplies. It does not apply to import bills of entry, delivery challans, or bills of supply. Certain classes of registered persons are excluded regardless of turnover under the proviso to Rule 48(4): insurers, banking companies and financial institutions including NBFCs, goods transport agencies supplying road transport services, passenger transport service suppliers, suppliers of services by way of admission to exhibition of cinematograph films in multiplex screens, SEZ units (note: SEZ developers are covered, units are not), and government departments and local authorities.

A B2C-heavy company above ₹500 crore has a separate obligation under Notification No. 14/2020-Central Tax to display a dynamic QR code on B2C invoices — a different requirement that is frequently confused with e-invoicing and should not be.

The 30-day reporting window

Since 1 April 2025, taxpayers with aggregate annual turnover of ₹10 crore or more cannot report an invoice to the IRP more than 30 days after the document date. The portal simply rejects it. There is no condonation, no late-fee mechanism, and no manual override. An invoice dated 1 August that reaches the IRP on 5 September is permanently unregisterable — which under Rule 48(5) means it is permanently not an invoice, and your customer permanently cannot claim the credit.

This is the single most damaging operational trap in the current framework, because it converts a bookkeeping backlog into an irreversible revenue loss.

Practical implications

Your customer loses input tax credit. Under Section 16(2)(a) of the CGST Act, a recipient can claim ITC only on the basis of a tax invoice or debit note issued under Section 31. If Rule 48(5) has voided your document, there is no valid invoice, and the ITC fails. Worse, e-invoice data auto-populates GSTR-1 and flows into the buyer's GSTR-2B. No IRN means no auto-population, which means the credit does not appear in GSTR-2B at all — and since 1 January 2022, Section 16(2)(aa) makes appearance in the auto-populated statement a condition of claiming credit. Your customer will notice. Enterprise buyers now run automated GSTR-2B reconciliation and withhold the tax component of payment until the credit lands.

The penalty is per invoice. Section 122(1)(i) of the CGST Act penalises supply of goods or services without issue of an invoice, or issue of an incorrect or false invoice, at ₹10,000 or the tax evaded, whichever is higher. Applied per document. A company issuing 300 non-compliant invoices a month is looking at a theoretical exposure of ₹30 lakh per month, before interest. Section 122(3)(e) separately penalises failure to issue an invoice in accordance with the Act at up to ₹25,000.

E-way bills stop working. For covered taxpayers, the e-way bill system now requires a valid IRN for the invoice being transported. No IRN, no Part-A generation via the invoice route. Goods movement stalls at the loading dock, not at a tax hearing.

GSTR-9C reconciliation exposes it. For companies above ₹5 crore turnover, the annual reconciliation statement compares turnover per audited financial statements against turnover reported in returns. A block of invoices booked in your books but absent from the e-invoice register is a visible, documented gap that an officer reads as either suppression or systemic non-compliance. Neither is a good conversation.

It surfaces in due diligence. Any funding round, acquisition, or bank credit facility involves a tax diligence workstream. "Was the company registered for e-invoicing from the correct date?" is a standard question. A gap becomes an indemnity, a holdback, or a reduction in valuation.

Step-by-step: what to do

Compute your aggregate turnover for every financial year from FY 2017-18 to FY 2025-26, at PAN level. Include exempt supplies, exports, and all GSTINs. Do not compute it GSTIN-by-GSTIN. If any single year exceeds ₹5 crore, you are covered — permanently, from the date the relevant notification made that threshold effective.
Verify your status on the portal rather than relying on your own arithmetic. Go to einvoice.gst.gov.in and use the "e-Invoice Status of Taxpayer" search with your GSTIN. The portal states whether you are enabled. If the portal shows you as enabled and you have not been generating IRNs, you have an existing exposure to quantify today.
If the portal shows you as not enabled but your own computation says you crossed the threshold, self-enable. The portal has a registration and self-enablement facility. Enablement status on the portal is not a legal defence — the obligation flows from the notification, not from the portal flag. Officers have consistently taken this position.
Choose an integration route and implement it. The options are direct API integration with an IRP, integration through a GST Suvidha Provider, the bulk generation offline utility for lower volumes, or the mobile app for very low volumes. If you are above ₹10 crore and subject to the 30-day window, an offline utility that depends on someone remembering to run it is not a control — build the API path.
Print the QR code on the invoice PDF. Rule 46(r) is a separate obligation from Rule 48(4). Generating the IRN but issuing the customer a PDF without the QR code is still a defective invoice.
Reconcile monthly: books versus e-invoice register versus GSTR-1. Three-way, every month, before filing. Any invoice in your books without an IRN must be identified within days, not at year-end. Build this into the close checklist, not the annual audit.
Fix historical gaps deliberately, with advice. Where the 30-day window has not expired, generate the IRN immediately. Where it has, the document cannot be regularised through the IRP — the position typically involves cancelling and re-issuing, with consequential GSTR-1 amendment and a commercial conversation with the buyer. Get this specific fact pattern reviewed before acting; the wrong sequence creates a second problem.
Note the separate MCA deadline running in parallel. The Companies Compliance Facilitation Scheme, 2026 has been extended by MCA General Circular No. 03/2026 to 31 August 2026, allowing pending annual filings to be cleared at normal fees plus only 10% of additional fees. If your GST house is being put in order this month, the ROC backlog should be cleared in the same pass — that window closes in under four weeks.

FAQ

Our turnover fell below ₹5 crore. Can we stop generating e-invoices?
No. The notification reads "in any financial year from 2017-18 onwards." There is no exit provision. Once covered, permanently covered.

The e-invoice portal does not show our GSTIN as enabled. Are we safe?
No. The portal flag is administrative; the obligation is statutory. If your aggregate turnover crossed the threshold, self-enable and start generating. Officers do not accept enablement status as a defence.

Do exports count towards the ₹5 crore aggregate turnover?
Yes. Section 2(6) includes exports and exempt supplies in aggregate turnover. Zero-rated does not mean excluded from the computation.

We missed the 30-day window on some invoices. Can we still get an IRN?
No. The IRP rejects them outright, with no condonation mechanism. Those documents fail Rule 48(5) and your buyer cannot claim credit on them. The remedy is cancellation and re-issue with a corresponding GSTR-1 amendment — take advice on sequencing before you touch it.

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