GST E-Invoicing: Threshold, IRN & Common Errors

TL;DR

GST e-invoicing is mandatory for businesses whose aggregate turnover in any preceding financial year exceeds ₹5 crore, under Notification 13/2020-CT as amended. Every B2B invoice must carry a unique 64-character Invoice Reference Number (IRN) generated by an Invoice Registration Portal (IRP) such as the government NIC portal, ClearTax, Cygnet, or 1Infinity. The IRN is paired with a dynamic QR code, and the data flows automatically into GSTR-1 — so there is no double entry. Below ₹5 crore, e-invoicing is voluntary but available. Cancellation is allowed only within 24 hours of IRN generation and only before GSTR-1 filing.

Quick Answer

You must generate an IRN for every B2B invoice (including credit notes, debit notes, and supplies to SEZ developers with tax) if your aggregate turnover crossed ₹5 crore in any preceding FY. The invoice is uploaded to an IRP, signed digitally, and returned with an IRN + signed QR code. The same data then auto-populates GSTR-1 Table 4 and 8.

For a quick self-check:

• Turnover up to ₹5 crore in the preceding FY → e-invoicing is voluntary.
• Turnover above ₹5 crore → e-invoicing is mandatory for all B2B invoices.
• Composition taxpayers, pure-B2C retailers, and pure-service exporters with no B2B supplies do not need e-invoicing regardless of turnover, though they may opt in voluntarily.

If you are unsure whether your business has crossed the threshold, check the GSTR-9 turnover of the previous FY or the GST Registration Eligibility Checker. For the broader registration question (when to register, threshold logic), see our Do I Need GST Registration? Checklist.

What E-Invoicing Actually Means

E-invoicing under GST is not “a digital PDF invoice.” It is a structured invoice in a specific JSON schema (Schema 1.1 / 2.0) that is uploaded to a government-recognized Invoice Registration Portal (IRP), digitally signed, and returned with two outputs:

• A 64-character alphanumeric Invoice Reference Number (IRN) generated by hashing the invoice payload with the seller’s GSTIN, document number, and document type.
• A signed QR code containing key invoice fields (IRN, GSTIN of supplier, GSTIN of recipient if B2B, invoice number, invoice date, invoice value, taxable value, GST rate, GST amount, IRN HSN code). For B2C invoices above ₹500, the QR code is mandatory but the IRN is optional under Notification 14/2020-CT.

The IRP then reports the invoice data to the GSTN, which propagates it into:

1. GSTR-1 of the supplier (auto-fills Table 4 for B2B, Table 6B for exports, Table 8 for credit/debit notes).
2. GSTR-2B of the buyer (auto-fills their eligible ITC for the month).
3. E-Way Bill portals (for invoices above ₹50,000 the system can generate Part A from IRN data).

This automation is why e-invoicing is more than a compliance checkbox — it eliminates double entry, reduces invoice-level mismatches, and pre-empts Section 16(2)(aa) rejections on the buyer’s side.

The Threshold and How It Changed

The threshold for mandatory e-invoicing has been progressively lowered since 2020. The current rule, set by Notification 13/2020-CT read with Notification 23/2021-CT (effective 1 April 2023), is:

Effective Date	Threshold (Aggregate Turnover in Preceding FY)	Notification
1 October 2020	₹500 crore	Notification 13/2020-CT
1 January 2021	₹100 crore	Notification 21/2020-CT
1 April 2021	₹50 crore	Notification 01/2021-CT
1 April 2022	₹20 crore	Notification 01/2022-CT
1 October 2022	₹10 crore	Notification 17/2022-CT
1 April 2023	₹5 crore	Notification 23/2021-CT

For FY 2026-27, every B2B invoice from a registered taxpayer with aggregate turnover above ₹5 crore in FY 2025-26 must carry an IRN and signed QR code.

Aggregate turnover for this purpose follows Section 2(6) of the CGST Act — the all-India turnover of all businesses with the same PAN, including exempt supplies, exports, and inter-State supplies, but excluding inward supplies on which reverse charge tax is paid by the recipient.

Who Must Generate IRN — Gujarat Industry Examples

The Gujarat business mix is unusually e-invoice heavy because of its manufacturing and export base. Below the threshold, e-invoicing is voluntary; above, it is mandatory.

Gujarat Industry Cluster	Typical Trigger for Mandatory E-Invoicing	Practical Note
Textiles & apparel (Surat, Ahmedabad)	Polyester yarn, man-made fabrics, readymade garments — turnover crosses ₹5 crore once a small-to-mid mill scales	Dyeing and job-work movements under Section 143 also require IRN on the delivery challan if the supplier is above the threshold.
Diamond & gems (Surat)	Even small polished-diamond merchants cross the threshold by H2 of their first export year	B2B invoices to jewellery exporters and HK/US buyers (zero-rated with LUT) need IRN for the supplier’s compliance even though the buyer’s ITC is nil.
Pharmaceuticals (Ahmedabad, Vatva, Sanand)	API manufacturers and formulation units routinely above ₹5 crore turnover	Batch-numbered invoices and the credit notes that follow product returns must each carry an IRN.
Chemicals & petrochemicals (Vadodara, Bharuch, Ankleshwar)	Specialised intermediates, paint inputs, dyes — high inter-State supplier base	Each inter-State invoice needs an IRN even if it is a B2B sale within Gujarat followed by a stock transfer to Maharashtra; both invoices need IRNs.
Ceramics & sanitaryware (Morbi, Himmatnagar)	Wall tiles, vitrified tiles, sanitaryware	Cluster is highly B2B (dealers, project sales). E-invoice workflow runs from the dispatch gate; integration with weighing bridges is common.
Engineering & manufacturing (Rajkot, Jamnagar, Ahmedabad)	Castings, fasteners, auto-ancillaries, brass parts	Auto-ancillary Tier-2 and Tier-3 suppliers above ₹5 crore are typical first-time e-invoice adopters in this cluster.
Agro & food processing (Anand, Mehsana, Rajkot)	Dairy, edible oil, spices, groundnut processing	GST rate-vs-code mismatches (5% vs 12%) on processed vs unprocessed foods are a common enforcement trigger around e-invoicing.
Maritime & ports (Mundra, Kandla, Porbandar, Bhavnagar)	Port services, ship chandling, EXIM logistics	E-invoice on port service charges to exporters is mandatory once the supplier’s turnover exceeds ₹5 crore.

If you operate in any of these clusters, run a quick check: is your FY 2025-26 aggregate turnover above ₹5 crore? If yes, every B2B invoice dated from 1 April 2026 must carry an IRN.

For businesses just crossing the threshold for the first time, the practical implication is that your invoicing software (Tally Prime, Zoho Books, Busy, Marg, or SAP B1) needs an IRN plug-in or API connection. Manual upload to the IRP works below 50 invoices a day but quickly becomes impractical above that.

How IRN Generation Actually Works

The IRN generation workflow is a five-step loop:

1. Build the invoice in your accounting system with all 60+ mandatory fields in the GST schema (Seller GSTIN, Document Number, Document Type, Document Date, Buyer details for B2B, line items with HSN, rate, taxable value, GST amount, total invoice value, place of supply, reverse-charge flag, etc.).
2. Send the JSON payload to the IRP via API (most common), bulk upload, or manual entry. There are six approved IRPs as of mid-2025 — the government NIC portal, ClearTax, Cygnet IRIS, 1Infinity, EazySwift, and Masters India. All six integrate with the same GSTN, so the IRN is universally valid.
3. IRP validates and signs the payload — checks for duplicate invoice numbers (same document number for the same GSTIN and FY is rejected), validates HSN rate pairings at a basic level, validates GSTIN format, and confirms buyer GSTIN if B2B. On success, returns the 64-character IRN, signed QR code (a base64-encoded PNG), and Acknowledgement Reference Number (ARN).
4. Print the invoice with IRN + QR code — the IRN and QR are part of the invoice by law. Most businesses print both on the invoice header and store the JSON response for audit trail.
5. Cancel within 24 hours if the invoice has an error — see the next section.

The whole round trip typically takes 2-5 seconds per invoice. Bulk upload can process 1,000 invoices in roughly 30 minutes.

Worked Example — A Surat Textile Trader’s E-Invoice

A polyester fabric trader in Surat with FY 2025-26 turnover of ₹7.2 crore sells 5,000 metres of dyed fabric to a garment exporter in Tirupur for ₹6.5 lakh (₹130 per metre) plus 5% CGST + 5% SGST = ₹32,500, total invoice ₹6,82,500. Steps:

1. Build invoice in Tally Prime with GST add-on. Document Number: ST/2026-27/000123. Document Date: 2026-09-05. Buyer GSTIN: 33ABCDE1234F1Z5 (Tirupur, Tamil Nadu). HSN code: 540752 (dyed woven fabric of synthetic filament yarn). Rate: 5%.
2. Tally add-on pushes JSON to the IRP via API. The IRP validates (no duplicate invoice number for this GSTIN, HSN 540752 exists in the master, 5% rate is permitted for this HSN). Returns:
   • IRN: c3e9... (64 chars)
   • Signed QR (base64 PNG embedded in the invoice)
   • ARN: 192340000012345
3. Invoice is printed with IRN + QR on the top-right corner, along with the standard tax-invoice fields.
4. The trader’s accountant opens GSTR-1 on 11 October — the entry is already there under Table 4A (B2B), populated by the IRP. No manual upload needed.
5. The garment exporter’s GSTR-2B for September 2026 picks up the entry on 14 September. The exporter claims the ITC (₹32,500) in their GSTR-3B for September.

Time saved per month: roughly 6-8 hours of manual entry for a business doing 200-300 B2B invoices per month.

Cancellation, Amendment, and the 24-Hour Window

E-invoice cancellation is one of the most misunderstood parts of the regime. The rule under Notification 13/2020-CT read with the IRP user guide:

• Cancellation is allowed only on the IRP (not by issuing a credit note on GSTR-1).
• Cancellation window is 24 hours from the time of IRN generation.
• Cancellation is allowed only before GSTR-1 filing for that period.
• A cancelled invoice cannot be edited — a fresh invoice with a new document number and new IRN must be issued if needed.

After the 24-hour window, the only way to correct an e-invoice is to:

• Issue a credit note (with its own IRN) against the original invoice if the correction is a value or quantity reduction, or
• Issue a debit note (with its own IRN) for additional charges, or
• Amend in the next period’s GSTR-1 Table 9 (Amendment Table) if the change is a GSTIN, HSN, or rate correction, or
• Reflect the cumulative correction in GSTR-9 at year-end.

Practical advice: if a Surat textile trader raises an invoice with a typo at 11 am and notices it at 2 pm the same day, the cleanest fix is to cancel the IRN by 11 am the next day and reissue with a new number. Once GSTR-1 is filed (typically the 11th of the following month), the correction path is GSTR-1 Table 9 + GSTR-9 reconciliation.

Common Mistakes

Based on our work with Gujarat taxpayers over the past 18 months, the recurring errors at the IRP and reconciliation layer are:

1. Duplicate invoice number. The IRP rejects an invoice if the same GSTIN has used the same document number for any document type in the same FY. The fix is to use a strict serial-numbering convention — letter prefix + FY suffix + 6-digit serial (ST/2026-27/000123) — and never reset at FY end without the FY marker.
2. Wrong HSN code or rate mismatch. The IRP does a soft validation but does not block — most HSN-vs-rate mismatches surface only at GSTR-2B reconciliation or in a Section 61 notice. Cross-check the rate against CBIC’s HSN-SAC master (the 2025 enforcement wave is described in our HSN Codes article).
3. Missing or wrong buyer GSTIN. For B2B invoices, the buyer GSTIN must be exactly 15 characters and active. If the buyer’s GSTIN is cancelled or suspended, the IRP accepts the invoice, but the buyer’s ITC claim fails and the buyer’s auditor flags the mismatch.
4. Inter-State flagged as intra-State (or vice versa). A supply from Ahmedabad to Surat is intra-State (CGST + SGST). A supply from Ahmedabad to Mumbai is inter-State (IGST). Wrong classification leads to GSTR-1 Table 4 vs Table 5 mismatch and Section 73 demand.
5. Cancellation missed within 24 hours. The most common workflow error — the accountant cancels the invoice in Tally but forgets to cancel the IRN on the IRP. The IRN stays active, GSTR-1 auto-populates the entry, and the supplier ends up paying tax on an invoice that was never billed. The recovery path is GSTR-1 Table 9 + GSTR-9 + a refund application.
6. Quotation issued with IRN. Quotations, proforma invoices, and delivery challans for non-supply movements should not carry an IRN. If the supplier mistakenly generates an IRN for a quotation, the same 24-hour cancellation rule applies. Treating a quotation as a tax invoice by mistake can trigger Section 122 penalty.
7. Multiple IRPs used inconsistently. Each IRP maintains its own authentication, API key, and cancelled-IRN log. Using ClearTax for some invoices and NIC directly for others is allowed, but cancellation must happen on the same IRP that generated the IRN. Mismatched IRP use causes audit-trail gaps.
8. E-invoice generated for a B2C invoice above ₹500. Notification 14/2020-CT requires a dynamic QR code on B2C invoices above ₹500 — but the IRN is mandatory only if the supplier is above the threshold. The common mistake is treating the IRN as required for all B2C invoices, which creates a fake IRN and a Section 122 exposure if the IRN cannot be reconciled to actual supply.

B2C QR Code vs B2B IRN — Two Different Requirements

Document Type	IRN Mandatory?	QR Code Mandatory?	Reference
B2B invoice	Yes (if supplier above ₹5 crore)	Yes (signed QR from IRP)	Notification 13/2020-CT
B2C invoice > ₹500	No (voluntary)	Yes (dynamic QR with payment link optional)	Notification 14/2020-CT
B2C invoice ≤ ₹500	No	No
Export invoice (with LUT)	Yes (if supplier above ₹5 crore)	Yes	Notification 13/2020-CT
Credit / debit note	Yes (if supplier above ₹5 crore)	Yes	Notification 13/2020-CT
Delivery challan (job-work, non-supply movement)	No	No

A common Gujarat retail scenario — a kirana store in Rajkot with ₹80 lakh turnover selling groceries to consumers does not need to generate IRNs but must carry a dynamic QR code on B2C invoices above ₹500 (the ₹500 limit refers to a single invoice, not cumulative sales). The QR can be static (basic) or dynamic (with payment link) — dynamic is recommended even for smaller stores because it enables UPI collection on the invoice.

What Happens If You Don’t Comply

For a registered taxpayer above the ₹5 crore threshold who continues to issue B2B invoices without an IRN:

• The IRP never receives the invoice. GSTR-1 auto-population does not happen. The taxpayer must manually upload the invoice in GSTR-1 — which itself is a non-compliance flag, since Section 37 mandates that GSTR-1 data match the IRN-generated data.
• The buyer’s GSTR-2B will not show the entry. The buyer loses ITC. The buyer raises a Section 16(2)(aa) dispute. The supplier typically receives a vendor complaint within 30 days.
• The assessing officer may invoke Section 122(1)(iii) — penalty of ₹10,000 or the tax amount involved, whichever is higher, per invoice.
• For repeated non-compliance, the assessing officer may escalate to Section 29 — cancellation of GSTIN after due SCN.

The enforcement priority in FY 2025-26 and FY 2026-27 is on the ITC chain integrity — the department’s automated matching between supplier GSTR-1 (with IRN data), buyer’s GSTR-2B, and the buyer’s GSTR-3B ITC claim. Missing IRN = unmatched ITC = disallowed credit + interest + penalty.

For the broader penalty framework (Section 47 late fee, Section 50 interest, Section 122 penalty, Section 29 cancellation), see our GST Penalty for Late Return Filing article.

How FinTax24 Sets Up E-Invoicing for Gujarat Businesses

For a Gujarat business crossing the ₹5 crore threshold for the first time, our standard onboarding is:

1. Turnover audit. Pull your GSTR-1 + GSTR-9 turnover for the preceding FY. Confirm whether you are above or below the threshold. If you are exactly at the threshold, we look at the cumulative trend — a single FY dip below ₹5 crore does not give relief; the trigger is aggregate turnover in any preceding FY.
2. Software integration. Most of our clients use Tally Prime, Zoho Books, or Busy Accounting. We configure the GST add-on (Tally: TallyPrime Gold + GST Add-on; Zoho Books: native GST + Zoho Invoice; Busy: built-in GST). We obtain API credentials from the chosen IRP (NIC is free; ClearTax, Cygnet, 1Infinity have nominal subscription plans) and map the schema.
3. First-pass invoice generation. We generate the first 50-100 invoices manually on the IRP to validate the data flow. Once the schema is right, bulk upload is enabled.
4. Cancellation protocol. A 24-hour rule on the IRP is operationalised with a Tally / Zoho Books workflow — any cancelled invoice must trigger an IRN cancellation within the window.
5. Monthly reconciliation. We reconcile GSTR-1 Table 4 with the IRP-issued IRNs, flag any mismatches, and follow up with suppliers whose GSTR-1 does not match the buyer’s GSTR-2B.

For businesses that prefer an end-to-end managed service, our GST Return Filing package includes e-invoicing, GSTR-1, GSTR-3B, GSTR-2B reconciliation, and annual GSTR-9. For first-time registrants crossing the threshold, our GST Registration service covers the onboarding flow and the IRP integration in the same engagement.

For the broader monthly return cycle (GSTR-1, GSTR-2B, GSTR-3B), see our GSTR-1 vs GSTR-3B explainer and the GSTR-2B vs GSTR-3B reconciliation guide.

When to Use an Expert

Self-service works when (a) your turnover is below ₹5 crore and e-invoicing is voluntary, (b) you have fewer than 50 B2B invoices per month, and (c) your accounting team understands the IRN cancellation rule.

Talk to a FinTax24 expert when any of these apply:

• You crossed ₹5 crore turnover in the preceding FY and need to enable e-invoicing within the current FY.
• You have an existing Tally / Zoho / Busy setup and need IRP API credentials, plug-in configuration, or schema mapping.
• You received a Section 122 notice for non-issuance of e-invoice, or a buyer complaint under Section 16(2)(aa) for missing IRN.
• You have multiple GSTINs (multi-State, separate unit registrations) and need a consistent e-invoice + e-way bill + GSTR-1 workflow.
• You are in a high-invoice-volume cluster (textile mills in Surat, ceramics in Morbi, pharmaceutical formulation in Ahmedabad) where the cancellation protocol and reconciliation cycle require dedicated handling.

For pan-Gujarat support — Ahmedabad, Surat, Vadodara, Rajkot, Bhavnagar, Gandhinagar, Jamnagar, Junagadh, the rest of the 33 districts, and the UT of Dadra & Nagar Haveli and Daman & Diu — our GST Return Filing service handles the end-to-end compliance including IRN generation, GSTR-1, GSTR-2B reconciliation, and the annual GSTR-9.

FAQ

What is the GST e-invoice threshold in FY 2026-27?

GST e-invoicing is mandatory for businesses whose aggregate turnover in any preceding financial year exceeded ₹5 crore. The threshold dropped to ₹5 crore effective 1 April 2023 via Notification 23/2021-CT and remains unchanged for FY 2026-27. Below the threshold, e-invoicing is voluntary but available.

What is an IRN and how is it generated?

An IRN (Invoice Reference Number) is a 64-character unique identifier generated by hashing the invoice payload with the seller’s GSTIN, document number, and document type. It is generated by a government-recognised Invoice Registration Portal (IRP) — the NIC portal, ClearTax, Cygnet, 1Infinity, EazySwift, or Masters India — after validating the JSON invoice against the GST schema.

Can I cancel an e-invoice after 24 hours?

No. Under Notification 13/2020-CT, an IRN can be cancelled only within 24 hours of generation and only before GSTR-1 filing for that period. After that, corrections must go through a credit note, debit note, GSTR-1 Table 9 amendment, or the annual GSTR-9 reconciliation.

Is e-invoicing mandatory for B2C invoices?

No. The IRN is mandatory only for B2B invoices (and credit/debit notes) when the supplier is above the ₹5 crore threshold. B2C invoices above ₹500 require a dynamic QR code under Notification 14/2020-CT, but the IRN itself is not required unless the supplier opts in voluntarily.

What is the difference between the IRN QR code and the B2C dynamic QR code?

The IRN QR is generated by the IRP, carries the IRN and key invoice fields, and is mandatory on every B2B invoice above the threshold. The B2C dynamic QR code is required on B2C invoices above ₹500, may carry a payment link (UPI), and is generated by the supplier’s invoicing system — not by the IRP.

Does e-invoicing replace GSTR-1?

No. E-invoicing auto-populates GSTR-1 with the IRN-validated invoice data, but GSTR-1 still has to be filed (with ARN) by the due date. For monthly filers, GSTR-1 is due by the 11th of the following month. The difference is that no manual upload is needed — the data flows from IRP to GSTR-1.

Do I need e-invoicing if I am a composition taxpayer?

No. Composition taxpayers are not required to generate e-invoices regardless of turnover. They file CMP-08 quarterly and GSTR-4 annually. The e-invoice mandate applies to regular taxpayers above the ₹5 crore threshold.

What happens if my buyer claims ITC but I have not generated IRN?

The buyer’s GSTR-2B will not reflect the invoice, so the buyer’s ITC claim fails under Section 16(2)(aa). The buyer typically raises a dispute within 30 days. The supplier’s fix is to generate the IRN immediately (subject to the original invoice date being within the permissible period under Section 31), and reflect the invoice in GSTR-1. If the original invoice date is more than 30 days old, the buyer may need to claim ITC only in the next return period where the IRN appears.

Which IRP should I use — NIC, ClearTax, Cygnet, 1Infinity, EazySwift, or Masters India?

All six IRPs integrate with the same GSTN, so the IRN is universally valid. The NIC portal is the most basic and free. ClearTax, Cygnet, and 1Infinity offer additional features (bulk upload, dashboards, e-way bill integration, reconciliation tools) at subscription plans starting at a few thousand rupees a year. For high-invoice-volume Gujarat businesses (textile mills, ceramics manufacturers, pharmaceutical units), a paid IRP is typically worth the cost.

Does e-invoicing apply to exports and SEZ supplies?

Yes. Exports and supplies to SEZ units / developers carry IRN regardless of whether they are zero-rated (with LUT) or taxable. The IRN generation is the same; the GST treatment (zero-rated vs taxed) flows through GSTR-1 Table 6A / 6B separately.

How does e-invoicing interact with e-way bills?

For invoices above the ₹50,000 e-way bill threshold, the e-way bill Part A can be auto-generated from the IRN data on most IRPs. The transporter still updates Part B (vehicle number) separately. The combined workflow reduces manual data entry on both portals and is standard practice for high-volume dispatch businesses.

What is the penalty for not issuing an e-invoice when required?

Section 122(1)(iii) prescribes a penalty of ₹10,000 or the tax amount involved, whichever is higher, per non-compliant invoice. For repeated non-compliance, the assessing officer may escalate to Section 29 — GSTIN cancellation after a show-cause notice. Additionally, the buyer’s ITC fails, leading to commercial disputes and Section 16(2)(aa) rejections.

Sources & References

• CBIC — Notification 13/2020-CT (e-invoicing mandate) and amendments
• CBIC — Notification 14/2020-CT (QR code for B2C invoices)
• GSTN — e-Invoice Portal
• GSTN — Approved IRPs list
• Income Tax / GST Department — gst.gov.in
• FinTax24 — GSTR-1 vs GSTR-3B and GSTR-2B vs GSTR-3B reconciliation

Disclaimer: This article reflects the e-invoicing rules understood at the time of publication (FY 2026-27). E-invoice thresholds, notification references, and IRP rules may change with subsequent CBIC notifications. Always cross-check the current Notification 13/2020-CT amendments and the active IRP list on the GSTN e-invoice portal before acting on a significant compliance change. Consider professional advice for first-time adoption or in case of a Section 122 / Section 16(2)(aa) dispute.