· 9 min read
By Correct Editorial — Compliance Research Desk
E-invoicing under GST: Everything You Need to Know
Published on: July 29, 2026
E-invoicing is the backbone of India's shift from periodic self-declaration to real-time, transaction-level tax reporting. Introduced under Rule 48(4) of the CGST Rules, 2017 and phased in through Notification No. 13/2020-Central Tax as amended, the mandate now applies to every registered person whose aggregate annual turnover has exceeded Rs 5 crore in any financial year since 2017-18.
The system's reach is now enormous. Successive threshold reductions — from Rs 500 crore in October 2020 to Rs 100 crore, Rs 50 crore, Rs 20 crore, Rs 10 crore, and finally Rs 5 crore from 1 August 2023 — brought several lakh additional taxpayers into scope, and the invoice registration infrastructure processes crores of documents every month across multiple portals.
The compliance consequence is unusually sharp. An invoice that should have carried an Invoice Reference Number (IRN) but does not is, in law, not an invoice at all. That single provision links e-invoicing to customer credit, e-way bill generation, GSTR-1 auto-population, goods movement, and audit defence. This guide explains scope, workflow, deadlines, failure consequences, and the controls a finance team needs.
What Is E-invoicing Under GST?
E-invoicing is not the generation of an invoice on a government portal. It is the process of reporting a structured invoice to an Invoice Registration Portal (IRP), which validates the data, assigns a unique IRN, digitally signs the document, embeds a QR code, and returns the signed payload to the supplier for issue to the customer.
The mechanics involve four elements:
- Schema INV-01 — the notified data structure containing mandatory and optional fields for supplier, recipient, line items, HSN, value, and tax
- IRN — a 64-character hash generated from supplier GSTIN, document type, document number, and financial year, guaranteeing uniqueness
- IRP — the registration portal, comprising the NIC-operated portals and additional private IRPs authorised by GSTN
- Digitally signed JSON and QR code — the authenticated output that must be reflected on the invoice issued to the buyer
Critically, the supplier continues to raise the invoice in its own ERP or billing system with its own numbering series. E-invoicing adds a registration and authentication layer, not a new document.
Who Must Issue E-invoices in 2026?
E-invoicing applies to registered persons with aggregate annual turnover (AATO) above Rs 5 crore in any financial year from 2017-18 onwards, for their B2B supplies, exports, deemed exports, and supplies to SEZ units. Once the threshold is crossed in any year, the obligation is permanent, even if turnover subsequently falls below Rs 5 crore.
Key scoping points frequently missed:
- AATO is PAN-level and PAN-India, aggregating all GSTINs, and includes exempt and export turnover
- Crossing mid-year triggers the obligation from the start of the immediately following financial year, or as specified in the relevant advisory
- The following categories remain exempt by notification: insurers, banking companies and financial institutions including NBFCs, goods transport agencies, suppliers of passenger transportation service, suppliers of admission to exhibition of cinematograph films in multiplex screens, government departments and local authorities, and SEZ units (note that SEZ developers are not exempt)
- Composition taxpayers, and persons issuing bills of supply for exempt supplies, are outside scope
Because thresholds are historical rather than current, the practical test for any entity is: has PAN-level aggregate turnover ever exceeded Rs 5 crore in any year since GST began? If yes, e-invoicing applies to covered supplies today.
Which Documents and Transactions Are Covered?
Three document types must be registered: tax invoices, credit notes, and debit notes, where the underlying supply is B2B, an export, a deemed export, or a supply to an SEZ unit or developer for authorised operations. Bills of supply, delivery challans, financial or commercial credit notes, and B2C invoices are outside the mandate.
| Document or transaction | E-invoice required |
|---|---|
| B2B tax invoice to a registered person | Yes |
| Export invoice, with or without payment of tax | Yes |
| Deemed export and SEZ supply | Yes |
| Credit note and debit note under Section 34 | Yes |
| Reverse charge invoice raised by the supplier | Yes, where the supplier is liable to issue it |
| Self-invoice for inward reverse charge from an unregistered supplier | No |
| B2C invoice | No, other than voluntary participation |
| Bill of supply for exempt or composition supply | No |
| Delivery challan and job work challan | No |
A separate voluntary B2C e-invoicing initiative with dynamic QR codes has been piloted for large retail-facing taxpayers. It is not mandatory, but the direction of travel is clear and system design should anticipate extension.
How Does the E-invoicing Workflow Operate?
The workflow runs from ERP to IRP and back, ideally within seconds and without manual intervention. The supplier generates the invoice, transmits the INV-01 JSON to an IRP through API, GSP, offline utility, or portal upload, and the IRP validates, deduplicates, signs, and returns the IRN and QR code.
- Generate the invoice in the ERP or billing system with complete mandatory fields, including recipient GSTIN, HSN, place of supply, and taxable value.
- Convert and transmit the data to the chosen IRP as INV-01 JSON, using direct API integration, a GST Suvidha Provider, or the bulk offline utility.
- Validation at the IRP — the portal checks schema compliance, GSTIN validity, mandatory field presence, and duplication of the IRN.
- IRN generation and digital signature — the IRP assigns the IRN, signs the payload, and generates the QR code.
- Return to the supplier — the signed JSON, IRN, and QR code are returned and must be stored against the invoice record.
- Issue to the customer with the QR code printed on the invoice, which the recipient can scan to verify authenticity.
- Downstream flow — e-invoice data auto-populates GSTR-1 and flows into the recipient's GSTR-2B and the Invoice Management System (IMS); Part A of the e-way bill can be generated from the same payload.
Two operational realities deserve emphasis. Cancellation is only possible within 24 hours of IRN generation and only in full; after that window, corrections must be made through credit notes or debit notes, which themselves require IRNs. And amendment is not available at the IRP — changes are made in GSTR-1 or GSTR-1A, which means the invoice data and return data can diverge if amendments are not tracked.
What Are the Reporting Time Limits?
Taxpayers with AATO of Rs 10 crore or more must report invoices, credit notes, and debit notes to the IRP within thirty days of the document date. The limit originally applied to AATO of Rs 100 crore and above from 1 November 2023, and was extended to the Rs 10 crore band from 1 April 2025. The portal rejects documents presented after the window.
The consequence of missing the window is severe and irreversible:
- The IRP will not accept the document, so no IRN can ever be generated for it
- Under Rule 48(5), the document is not a valid tax invoice, and the supply is effectively undocumented
- The supplier still owes output tax on the supply, but the customer has no valid document to claim credit
- Remediation typically requires cancelling the commercial document and issuing a fresh, correctly dated invoice, with attendant revenue-recognition and customer-relationship consequences
Back-dated invoicing, month-end batch processing, and manual approval queues are the most common causes of breach. Any process that allows an invoice to sit unregistered for weeks is a structural control failure.
What Happens If You Do Not Comply?
Non-compliance carries statutory penalties, credit denial for customers, and physical risk to goods in transit. Section 122(1) of the CGST Act prescribes a penalty of Rs 10,000 or the tax evaded, whichever is higher, per invoice for failing to issue an invoice in the prescribed manner, and Rs 25,000 per invoice for an incorrect or improper invoice.
The wider exposure includes:
- Customer ITC denial, since an invoice without an IRN is not a valid document under Section 16(2)(a) read with Rule 48(5)
- Detention and seizure under Section 129 where goods move without a valid invoice and e-way bill
- Reconciliation breaks between books, GSTR-1, and GSTR-2B that surface in departmental scrutiny and annual reconciliation in GSTR-9C
- Commercial friction — large buyers increasingly withhold payment until a valid IRN-bearing invoice is provided
- Audit and diligence findings, where unregistered invoices become a quantified contingent liability
How Does E-invoicing Connect to Returns, IMS, and ITC?
E-invoice data is the source record for the entire downstream chain. Registered invoices auto-populate Table 4 onwards of GSTR-1, flow to the recipient's GSTR-2B and IMS dashboard, and determine what credit the buyer can accept, reject, or keep pending.
The linkages that matter operationally:
- GSTR-1 auto-population reduces keying effort but shifts the control point upstream — an error in the IRN payload becomes an error in the return
- Hard-locking of auto-populated liability in GSTR-3B means outward tax cannot be quietly adjusted at the return stage; corrections must flow through GSTR-1A
- IMS allows recipients to accept, reject, or keep records pending, so a supplier's late or incorrect e-invoice directly delays the customer's credit
- E-way bill integration allows Part A generation from the e-invoice payload, avoiding duplicate data entry for goods movement
The practical takeaway is that invoice-level accuracy at the point of registration now determines return accuracy, customer credit, and dispute exposure. For the recipient-side rules, see Input Tax Credit (ITC): Rules and Best Practices; for the return mechanics, see GSTR-1 vs GSTR-3B: Key Differences Explained.
Practical Recommendations
E-invoicing failures are almost always process failures rather than knowledge failures. Build the following controls into the invoicing lifecycle.
- Automate IRN generation at invoice creation. Register synchronously through API or GSP integration so that no invoice can be issued to a customer without an IRN.
- Run a daily unregistered-invoice exception report. Any document more than one day old without an IRN should escalate automatically, well inside the thirty-day window.
- Validate master data continuously. Customer GSTIN status, place of supply, HSN codes, and unit-of-measure codes are the top causes of IRP rejection; schedule periodic GSTIN validity checks against the portal.
- Store the signed JSON and QR code against each invoice for the statutory retention period, since the signed payload is the primary evidence of compliance.
- Control the 24-hour cancellation window with a defined approval path, and train billing teams to use credit notes with IRNs beyond it.
- Reconcile three ways every month — books, IRP data downloaded from the portal, and GSTR-1 as filed — before the return due date.
- Monitor the turnover trigger. Track PAN-level AATO quarterly so that crossing Rs 5 crore, or the Rs 10 crore reporting-window band, is identified before the obligation begins.
- Confirm exemption status in writing. If relying on an exemption such as GTA or SEZ unit status, document the notification basis, because exemptions are entity-specific and frequently misapplied.
References
- E-invoice portal — Official IRP — Schema, API documentation, and taxpayer enablement status
- NIC e-invoice portal — Bulk generation utilities, master codes, and validation rules
- CBIC-GST — CGST Rules, Rule 48 — Legal basis for e-invoicing and consequences of non-compliance
- CBIC — Central Tax notifications — Notification No. 13/2020-Central Tax and subsequent threshold amendments
- GST Portal — Advisories and releases — Reporting time limit and enablement advisories
- E-way bill portal — Integration of e-invoice data with Part A of the e-way bill
- ClearTax — E-invoicing under GST — Implementation guidance and FAQs
- TaxGuru — E-invoicing compliance analysis — Penalty exposure and procedural commentary
- Tally Solutions — E-invoicing setup guidance — ERP configuration and exception handling
Frequently asked questions
- Who is required to generate e-invoices under GST?
- Every registered person whose aggregate annual turnover exceeded Rs 5 crore in any financial year from 2017-18 onwards must generate e-invoices for B2B supplies, exports, deemed exports, and supplies to SEZ units, along with related credit and debit notes. Notified exempt categories include banks, insurers, goods transport agencies, passenger transport, and SEZ units.
- What is the time limit for reporting an invoice to the IRP?
- Taxpayers with aggregate annual turnover of Rs 10 crore or more must report invoices and credit or debit notes to an Invoice Registration Portal within thirty days of the document date. The portal rejects late submissions outright, leaving the supplier with an unregistered document that cannot be treated as a valid tax invoice.
- Is an invoice without an IRN valid under GST?
- No. Rule 48(5) of the CGST Rules provides that where e-invoicing applies, any invoice issued other than in the prescribed manner is not treated as an invoice at all. The recipient consequently loses input tax credit, goods in transit can be detained, and the supplier faces penalty under Section 122 of the CGST Act.
- Does e-invoicing apply to B2C supplies?
- Mandatory e-invoicing covers B2B supplies, exports, deemed exports, and SEZ supplies, not B2C transactions. A voluntary B2C e-invoicing initiative with dynamic QR codes has been piloted for large retail-facing taxpayers, and businesses should monitor GSTN advisories since extension of scope has been signalled.