GST invoicing rules govern the format, content, and timeline for tax invoices, debit/credit notes, and e-invoicing. Section 31-34 of the CGST Act and Rules 46-55 prescribe mandatory fields, e-invoice thresholds, and document requirements.
When: Every taxable supply of goods/services
Issuance: Before or at the time of removal of goods / delivery. For services: within 30 days of supply (45 days for banking/insurance).
When: By composition dealers OR for exempt supplies
Issuance: Same timeline as tax invoice. No tax breakup shown (since no GST charged).
When: Taxable value or tax charged in invoice is LESS than actual
Issuance: When additional amount needs to be charged to recipient. Example: price increase after invoice issued.
When: Taxable value or tax charged in invoice is MORE than actual, or goods returned
Issuance: Must be issued before: (a) 30th November of following FY, OR (b) date of filing annual return — whichever is earlier.
When: Advance payment received before supply
Issuance: At the time of receipt of advance. If supply is made subsequently: issue tax invoice and adjust advance.
When: Advance received but supply not made, and refund issued
Issuance: At the time of refund of advance. Used when transaction is cancelled after advance payment.
Mandatory for businesses with aggregate turnover > ₹5 Cr (from August 1, 2023). Previously: ₹10 Cr (Oct 2022), ₹20 Cr (Apr 2022), ₹50 Cr (Apr 2021), ₹100 Cr (Jan 2021), ₹500 Cr (Oct 2020). Government may further lower the threshold.
Generate invoice in accounting software → Upload JSON to IRP (Invoice Registration Portal) → IRP validates and returns: IRN (Invoice Reference Number, 64-char hash), digitally signed QR code, signed e-invoice. Invoice is now valid.
Primary: einvoice1.gst.gov.in (NIC). Backup: einvoice2.gst.gov.in. Private IRPs also authorized (e.g., ClearTax, Cygnet). All IRPs connect to GST system.
Unique 64-character hash generated by IRP. Based on: Supplier GSTIN + FY + Document Type + Document Number. Once generated: invoice cannot be modified. Can be cancelled within 24 hours only.
E-invoice data auto-populates: GSTR-1 (outward supply), e-way bill Part A (if shipping details provided). No separate GSTR-1 entry needed for e-invoiced supplies.
Not required for: SEZ units, insurers, banking companies, GTA, passenger transport, cinema tickets, OIDAR services. Bill of Supply (composition dealers, exempt supplies): not covered.
A registered person must issue a tax invoice for every taxable supply of goods or services (Section 31). For goods: before or at the time of removal/delivery. For services: within 30 days of supply (45 days for banking/financial services/insurance). For continuous supply: at the time of each payment or milestone. No invoice needed for supplies below ₹200 (if recipient doesn't demand). Reverse charge: recipient must issue self-invoice within 30 days.
E-invoicing is the electronic authentication of B2B/B2G invoices through the government's Invoice Registration Portal (IRP). It generates an IRN (Invoice Reference Number) and QR code for each invoice. Currently mandatory for turnover > ₹5 Cr. Process: generate invoice normally → upload to IRP via API/portal → IRP validates and returns signed invoice. Benefits: auto-populates GSTR-1 and e-way bill, reduces fraud, enables real-time tax data for government.
Cancel: Within 24 hours of IRN generation on the IRP portal. After 24 hours: cannot cancel on IRP. Workaround: issue a credit note (which also needs to be e-invoiced) to nullify the original invoice. Modify: E-invoices CANNOT be modified once IRN is generated. If changes needed: cancel within 24 hours and re-generate, or issue debit/credit note for adjustments.
Section 34: Credit note must be issued on or before the EARLIER of: (1) 30th November of the financial year following the year of original invoice, or (2) Date of filing annual return (GSTR-9) for that year. Example: For an invoice dated 15-Aug-2025, credit note must be issued before 30-Nov-2026 or GSTR-9 filing date for FY 2025-26 — whichever is earlier. After this: no credit note can be issued and output tax cannot be reduced.
Depends on aggregate turnover: (1) Up to ₹5 Cr: 4-digit HSN/SAC code required on B2B invoices (optional on B2C), (2) Above ₹5 Cr: 6-digit HSN/SAC code required. Notification 78/2020: made HSN mandatory on all tax invoices from April 2021. E-invoicing: 4 or 6 digits as per turnover slab. Incorrect HSN: may lead to mismatch in GSTR-1 and ITC issues for recipient.
Generate e-invoices with auto IRN, manage debit/credit notes, and ensure every invoice has all mandatory fields.
Start Free TrialThe monthly contribution upload, MC template columns and reason codes
The ECR 2.0 text format, the 11 fields and the EPFO portal walkthrough
Check a product's rate in the GST Rate Finder, or see how Laabam One handles GST billing and returns.