A GST tax invoice must show the supplier's name, address and GSTIN, a unique serial number of up to 16 characters, the date, the buyer's name, address and GSTIN (for a registered buyer), HSN or SAC, quantity, taxable value, rate and amount of CGST, SGST or IGST, the place of supply and a signature (Rule 46, CGST Rules). This generator fills all of these and prints on A4.
How the invoice is calculated
- Taxable value of each line = quantity × rate (enter the rate after any discount).
- Tax on each line = taxable value × GST % of that line, rounded to the paisa. Lines can carry different rates.
- If the seller's state and the buyer's state are the same, each line's tax is split half CGST and half SGST; if they differ, it is all IGST. The place of supply printed is the buyer's state.
- Gross total = taxable value + all taxes. The total is rounded to the nearest rupee and the difference is shown as round-off, which is the common trade practice.
- The rounded total is written in words using the Indian system: thousand, lakh, crore.
Worked example
Sharma Traders in Pune (Maharashtra, state code 27) sells to Patel Hardware Pvt Ltd in Surat (Gujarat, code 24). The states differ, so the sale is inter-state and carries IGST.
| Item | HSN | Qty × rate | Taxable | IGST 18% |
|---|---|---|---|---|
| Steel hinges 4 inch | 8302 | 200 × ₹45 | ₹9,000.00 | ₹1,620.00 |
| Wood screws (box of 100) | 7318 | 50 × ₹120 | ₹6,000.00 | ₹1,080.00 |
| Total | ₹15,000.00 | ₹2,700.00 |
Invoice total: ₹17,700, in words "Rupees Seventeen Thousand Seven Hundred Only". Had the buyer been in Nashik, the same ₹2,700 would print as CGST ₹1,350 and SGST ₹1,350. If the gross had come to ₹14,567.69, the invoice would show a round-off of +₹0.31 and a total of ₹14,568.
Things to check before you send it
- Your GSTIN and the buyer's GSTIN. The tool checks the format and fills the state from the first two digits; use the GSTIN validator for a full breakdown and FundRaksha Trust for the live status. Credit taken on an invoice with a wrong GSTIN goes to the wrong account.
- Serial numbers run without gaps in each financial year; a fresh series is common from 1 April.
- Unregistered (B2C) buyer: leave the GSTIN blank. For a B2C invoice of ₹50,000 or more the buyer's name, address and the state of delivery are also required under Rule 46.
- If your aggregate turnover crossed ₹5 crore in any year since 2017-18, a printed invoice is not enough for B2B sales: it needs an IRN from the Invoice Registration Portal. Check with the e-invoice limit checker.
- Rates: use the GST calculator to confirm the slab after the September 2025 changes.
When to move to proper billing software
This page is good for the occasional invoice. It does not save anything, so you have to keep your own copy and your own sequence of numbers. Save, track and send invoices free with FundRaksha Book: invoice numbers run automatically, the rate comes from the HSN code, stock updates as you bill, invoices go out on WhatsApp and email, and your GSTR-1 data is ready at month end. The first 300 invoices are free.
Sources
- cbic-gst.gov.in (CGST Rules, 2017, Rule 46: tax invoice)
- cbic-gst.gov.in (Notification No. 78/2020-Central Tax, dated 15 October 2020: HSN digits o
- cbic-gst.gov.in (Notification No. 10/2023-Central Tax, dated 10 May 2023: e-invoicing abov
- idtc.icai.org (Notification No. 9/2025-Central Tax (Rate), dated 17 September 2025, in for
- taxinformation.cbic.gov.in (Notification No. 19/2025-Central Tax (Rate), dated 31 December
- gstcouncil.gov.in (56th GST Council meeting, 3 September 2025, rate rationalisation)