GST E-Invoicing: Applicability, the 30-Day Reporting Rule and Common Errors

GST e-invoicing is now a routine part of billing for most mid-sized businesses. A B2B invoice is valid only after it is reported to the Invoice Registration Portal (IRP) and receives an Invoice Reference Number (IRN) and a signed QR code. The data then flows into GSTR-1, the recipient’s GSTR-2B and the Invoice Management System (IMS), which reduces reconciliation effort on both sides.

This guide explains who must issue e-invoices, which documents are covered, the 30-day reporting rule for larger businesses, and the errors that most often cause rejected IRNs or credit problems for customers.

Key takeaways

• E-invoicing applies to registered persons whose aggregate turnover exceeded ₹5 crore in any financial year from 2017-18 onwards.
• It covers B2B supplies, exports, supplies to SEZs, and related credit and debit notes; B2C invoices are outside the IRN requirement.
• Businesses with aggregate annual turnover of ₹10 crore or more must report invoices and credit notes to the IRP within 30 days of the document date, from 1 April 2025.
• Some sectors, such as banking and insurance companies, goods transport agencies and SEZ units, are exempt.
• An IRN can be cancelled only within 24 hours; after that, corrections go through credit notes or GSTR-1 amendments.

Who must follow GST e-invoicing

The test is simple: if aggregate turnover, computed on a PAN basis across all GSTINs, crossed ₹5 crore in any financial year from 2017-18, e-invoicing applies from the date notified, and continues even if turnover later falls.

Common exemptions

Category	Status
SEZ units (not SEZ developers)	Exempt
Insurance companies, banks, NBFCs and other financial institutions	Exempt
Goods transport agencies	Exempt
Passenger transport services	Exempt
Admission to cinema halls (multiplex screens)	Exempt
Government departments and local authorities	Exempt

Exemptions apply to the entity, not to a particular invoice, so check the exact wording of the notification before relying on one.

Documents covered

• Tax invoices for B2B supplies
• Export invoices and supplies to SEZ units or developers
• Deemed exports
• Credit notes and debit notes issued against these
• Reverse charge invoices raised by suppliers where the recipient pays tax

B2C invoices, delivery challans and bills of supply to unregistered persons do not need an IRN. Very large businesses have a separate dynamic QR code requirement on B2C invoices.

The 30-day reporting rule

For businesses with aggregate annual turnover of ₹10 crore or more, the IRP does not accept an invoice or credit note that is more than 30 days old on the date of reporting. The rule started in November 2023 for businesses with turnover of ₹100 crore or more and was extended to the ₹10 crore threshold from 1 April 2025.

Worked example

A manufacturer with turnover of ₹40 crore issues an invoice dated 1 September 2026. Its ERP integration fails and the invoice is not reported. Following the GSTN’s own illustration (an invoice dated 1 April cannot be reported after 30 April), the last day to obtain an IRN is 30 September 2026. On 1 October the IRP rejects it.

Because the invoice without an IRN is not a valid B2B tax invoice, the supplier must issue a fresh invoice with a current date and report it immediately. The customer’s credit then flows in a later period, which can strain the relationship and trigger questions about the delay. A daily exception report of unreported invoices avoids this.

How e-invoice data flows

1. The supplier’s ERP or billing system generates JSON in the standard schema.
2. The IRP validates it, generates the IRN, digitally signs it and returns a QR code.
3. The supplier prints the QR code on the invoice sent to the customer.
4. Data auto-populates the supplier’s GSTR-1 and, where applicable, the e-way bill Part A.
5. The recipient sees it in IMS and GSTR-2B for accepting, rejecting or keeping pending.

Because GSTR-1 is auto-populated, differences between e-invoice data and GSTR-3B are easy for the system to spot. Our guide to the DRC-01B GSTR-1 vs GSTR-3B mismatch notice explains what happens when they do not match.

Common e-invoicing errors and fixes

Error	Cause	Fix
Duplicate IRN	Same invoice number reported twice in the year	Use unique document numbers per GSTIN per financial year
Invalid recipient GSTIN	Cancelled or mistyped GSTIN	Validate customer GSTIN before billing
HSN not valid	Wrong or short HSN code	Keep item masters updated with correct HSN digits
Tax rate mismatch	Old rate after GST 2.0 changes	Update rates in the item master from 22 September 2025
Invoice older than 30 days	Late reporting	Daily monitoring and a fresh invoice where rejected
Wrong place of supply	Intra-state vs inter-state error	Map customer state codes correctly

Cancelling or amending an e-invoice

• An IRN can be cancelled on the IRP within 24 hours of generation; partial cancellation is not allowed.
• After 24 hours, the IRP cannot cancel it. Corrections are made by issuing a credit note or debit note, or amending details in GSTR-1 where permitted.
• The same invoice number cannot be reused after cancellation.

Consequences of not issuing e-invoices

• An invoice issued without an IRN, where one is required, is not treated as a valid invoice, which can affect the customer’s input tax credit.
• Penalties can apply for issuing invoices in contravention of the rules.
• E-way bills generated without e-invoice data may also be questioned in transit.

For businesses newly crossing ₹5 crore, it helps to align e-invoicing with the monthly GSTR-2B vs GSTR-3B reconciliation so both sales and purchase data stay clean.

Frequently asked questions

What is the turnover limit for GST e-invoicing?

E-invoicing applies if aggregate turnover exceeded ₹5 crore in any financial year from 2017-18 onwards, computed on a PAN basis.

What is the 30-day rule for e-invoices?

Businesses with aggregate annual turnover of ₹10 crore or more cannot report an invoice or credit note to the IRP if it is more than 30 days old. This applies from 1 April 2025.

Is e-invoicing required for B2C sales?

No IRN is required for B2C invoices. Very large businesses must instead print a dynamic QR code on B2C invoices.

Can an e-invoice be cancelled?

Yes, within 24 hours of generating the IRN, and only in full. After that, use a credit or debit note or amend the details in GSTR-1.

This article is general information based on the law as of September 2026, and is not legal or tax advice. Please check the facts of your own case with a professional before acting.