e-Invoicing Under GST: Applicability, Limits, Rules & Process

E-invoicing under GST is a system where B2B invoices are electronically authenticated by an Invoice Registration Portal (IRP) and the government does not create invoices but validates them; businesses continue to generate the invoice in their ERP and then report it to the IRP. The IRP validates the invoice data, generates a unique Invoice Reference Number (IRN), a 64-character hash, digitally signs the JSON payload and returns a signed invoice with a QR code for offline verification. Once validated, the invoice details are automatically made available to the GST portal (draft GSTR-1) and to the e-way bill system (Part A), reducing manual entry and reconciliation. This process prevents duplicate or fake invoices and helps in real-time matching of ITC claims and output tax.

E-invoicing is mandatory for businesses whose aggregate annual turnover exceeds Rs. 5 crore in a financial year, effective from August 1, 2023. Previously higher thresholds applied in phased rollouts, but the current notified limit requires all taxpayers above Rs. 5 crore turnover to report their B2B invoices to an IRP. Note that the rule applies to B2B supplies and specified document types (tax invoices, debit/credit notes) and some notified categories and transactions are excluded. Businesses below the turnover threshold are not mandated but may adopt e-invoicing voluntarily if they wish.

You must report B2B tax invoices, debit notes and credit notes in the prescribed JSON schema (GST INV-01) to the IRP for e-invoicing. The e-invoice schema corresponds to Form GST INV-1 and requires supplier, recipient, item-level, value and tax breakup fields; non-tax invoices like bill of supply, bill of entry, ISD invoices and certain delivery challans are excluded. Specific notified businesses (for example insurers, banks, GTA, passenger transport suppliers, cinema multiplex services, certain SEZs and government departments as exempted) have tailored exclusions via CBIC notifications. Always ensure the invoice is uploaded within the statutory time limit and in the correct JSON format to generate an IRN and signed QR code.

Mandatory e-invoice fields include supplier and recipient GSTIN, invoice number and date, invoice value (taxable and tax), number of line items with HSN, place of supply (state code), and the IRN and its generation date once issued. If any mandatory field is incorrect, for example wrong recipient GSTIN, duplicate invoice number, or incorrect place of supply, the IRP will reject the JSON and you will not receive a valid IRN, making the document an invalid tax invoice under Rule 48(4) and exposing you to penalties and denial of ITC for recipients. Small clerical mismatches commonly cause validation errors, so accurate data entry and ERP-to-IRP validation are critical. Corrections generally require cancelling and reissuing the invoice subject to time and cancellation rules.

First, the supplier generates the invoice in their accounting/ERP system in the prescribed JSON schema (GST INV-01); next, the invoice JSON is uploaded to the IRP (via API, Excel mode, FTP/SFTP or Tally connector). The IRP validates the data and, upon success, generates a 64-character IRN, digitally signs the invoice, and returns a signed JSON with a QR code; this signed invoice data is simultaneously pushed to the GST portal (draft GSTR-1) and the e-way bill system (Part A) where applicable. The signed IRN and QR code are used for authentication and offline verification by the buyer or tax authorities, and the workflow reduces manual reconciliations and transcription errors. Failed validations must be corrected in the ERP and re-submitted within the allowed timelines.

An IRN must be generated by uploading the invoice to the IRP within 30 days from the date of invoice generation; invoices not reported within this period cannot be validated later as a backend IRN. If you need to cancel a generated e-invoice, cancellation is permitted on the IRP only within 24 hours of IRN generation and partial cancellations are not allowed. These strict timelines mean businesses must ensure correct invoice details before reporting and have operational processes to handle cancellations quickly when needed. Non-adherence can lead to the invoice being treated as invalid and potential penalties for both supplier and recipient.

If a notified taxpayer issues a B2B invoice without generating a valid IRN from the IRP, that invoice is treated as an invalid tax invoice under Rule 48(4) and may attract penalties and denial of input tax credit to the recipient. Besides Rule 48(4) consequences, inaccuracies or failure to report can invite interest, penalties under GST provisions for incorrect tax invoices, and enforcement actions during audits due to mismatch in system-level records. Recipients relying on such invoices may face blocked or delayed ITC claims, so both supplier and recipient face financial and compliance risks. Maintaining accurate, timely e-invoice reporting and storing signed JSON/QR codes helps demonstrate compliance in assessments.

The main benefits of e-invoicing are automated reporting into GST returns and e-way bills, reduced transcription errors, real-time invoice trail for tax authorities which curbs fake ITC claims, and faster reconciliation and tracking of invoices. Practical challenges include ERP integration and JSON validation errors, strict reporting and cancellation timelines (30 days for reporting, 24 hours for cancellation), frequent data validation rejections (wrong GSTIN, duplicate invoice numbers, HSN mismatches), and operational dependency on internet connectivity and IRP/GST portal uptime for high-volume users. Businesses can mitigate these challenges with robust integration, pre-validation checks, and using high-availability middleware or approved IRPs that offer retries, bulk modes and enriched validation features. For large volumes, using an IRP-approved solution with uptime guarantees and auto-retry for e-way bills reduces failures and manual workarounds.

Key technical components of an e-invoice are the JSON payload in the prescribed GST INV-01 schema, the Invoice Reference Number (IRN), a unique 64-character hash generated by the IRP, a digitally signed JSON returned by the IRP, and a QR code that embeds supplier and recipient GSTIN, invoice number and date, invoice value, HSN, IRN and IRN generation date for offline verification. The digital signature authenticates the sender and ensures the signed invoice content is tamper-proof; the QR code allows quick scanning and verification at the buyer’s end or during verification by authorities. Proper construction and submission of the JSON schema from the ERP is essential to pass IRP validation and receive the signed IRN and QR code back for invoicing records and GST filing automation.