What goes on a GST invoice
A tax invoice in India must carry the fields listed in Rule 46 of the CGST Rules, 2017. Any invoice that skips a required field is non-compliant and the buyer may be unable to claim input tax credit on it. The mandatory fields are: supplier's name, address, and GSTIN; consecutive invoice number (≤16 characters, unique per financial year); date of issue; recipient's name, address, and GSTIN (for B2B supplies above ₹50,000, or on request); HSN or SAC code; description, quantity, unit, and rate of each supply; total taxable value, discount, and net value; the applicable GST rate split into CGST + SGST for intra-state or IGST for inter-state; place of supply (for inter-state); address of delivery if different from place of supply; whether the tax is payable on reverse charge; and the supplier's signature or digital signature.
Intra-state vs inter-state supply
If the place of supply is in the same state as your registered business, you charge CGST + SGST (split equally). If it's in a different state or a Union Territory, you charge IGST at the full applicable rate. Exports are treated as inter-state supplies, you can either pay IGST and claim a refund later, or make the supply under a Letter of Undertaking (LUT) without paying IGST, per Section 16 of the IGST Act.
HSN and SAC codes, current rules
HSN codes classify goods; SAC codes classify services. Per CBIC Notification 78/2020 (Central Tax), the number of HSN digits required on your invoice depends on your Aggregate Annual Turnover (AATO) in the previous financial year:
- AATO above ₹5 crore: 6-digit HSN mandatory on every invoice, both B2B and B2C.
- AATO up to ₹5 crore: 4-digit HSN mandatory on B2B invoices; optional on B2C.
- Exports / SEZ supplies: 8-digit HSN required regardless of turnover.
AATO is calculated PAN-wise, every GSTIN under a single PAN is added together. Missing or wrong HSN can attract a penalty of ₹50 per invoice (cap ₹25,000 per year) under Section 125 of the CGST Act.
E-invoice threshold and the 30-day IRN rule
Two separate rules apply once your turnover crosses certain thresholds:
- Above ₹5 crore AATO: from 1 August 2023, you must generate e-invoices via the Invoice Registration Portal (IRP), per CBIC Notification 10/2023. The IRP returns an Invoice Reference Number (IRN) and a signed QR code that must appear on the invoice you give the buyer.
- Above ₹10 crore AATO: from 1 April 2025, every invoice must be reported to the IRP within 30 days of the invoice date. Late uploads are rejected and the invoice becomes invalid for GST purposes, your buyer can't claim ITC on it.
This generator creates a valid printable invoice. If e-invoicing applies to you, upload the invoice to the IRP first to get an IRN and QR before issuing it to the buyer.
Invoice vs bill of supply
A tax invoice is issued for taxable supplies by a GST-registered dealer. A bill of supply is issued by composition-scheme dealers (Section 10) and for exempt supplies, per Rule 49. Use the bill-of-supply option when you're registered under composition scheme, you can't charge GST on a bill of supply.
Common mistakes to avoid
- Skipping the place of supply on inter-state invoices. Required under Rule 46(n) and your buyer can't claim IGST input credit without it.
- Using the same invoice number across financial years. Numbers must be unique per FY. Reset on 1 April.
- Missing the reverse-charge declaration. Under Rule 46(p), the invoice must state whether tax is payable on reverse charge. For supplies under Sec 9(3)/9(4), this is mandatory.
- Using special characters in the invoice number. Only alphanumerics, hyphen, and slash are allowed, per Rule 46(b).