GST Tax Invoices in India, Explained
What a GST tax invoice in India must show: GSTIN, HSN/SAC, place of supply, CGST + SGST vs IGST, a worked example with rounding, and e-invoicing rules.
By Udit Agarwal · Updated October 17, 2026
A GST tax invoice is the bill a registered supplier in India issues for a taxable sale, and Rule 46 of the CGST Rules, 2017 lists what it must show: the supplier's GSTIN, a unique invoice number and date, the recipient's details, an HSN or SAC code for each item, the taxable value, the tax rate and amount, and the place of supply. GST on a supply within one state is split into equal halves of CGST and SGST, while a supply between states is charged IGST at the full rate. The total tax is the same either way.
In plain terms, Rule 46 asks for:
| Detail | What is required |
|---|---|
| Supplier | Name, address and GSTIN |
| Invoice number | Consecutive, at most 16 characters (letters, digits, hyphen and slash), unique within the financial year |
| Date | The date of issue |
| Recipient | Name, address and GSTIN if registered; for an unregistered buyer, name, address and state with its code once the taxable value is ₹50,000 or more |
| Items | Description, HSN code for goods or SAC for services, quantity and unit |
| Values | Total value, and taxable value after any discount |
| Tax | Rate and amount of CGST, SGST or UTGST, IGST, and cess where it applies |
| Place of supply | With the state's name, for inter-state supplies |
| Delivery address | Where it differs from the place of supply |
| Reverse charge | Whether the recipient pays the tax under reverse charge |
| Signature | Signature or digital signature of the supplier or an authorised person |
Take the made-up GST Identification Number 29ABCDE1234F1ZW:
| Characters | Example | Meaning |
|---|---|---|
| 1–2 | 29 | State code: 29 is Karnataka, 27 Maharashtra, 07 Delhi |
| 3–12 | ABCDE1234F | The business's PAN |
| 13 | 1 | Which registration this is for that PAN in the state (1–9, then A–Z) |
| 14 | Z | Z by default |
| 15 | W | A check character calculated from the first 14 |
A GSTIN that fails the check has been mistyped. Passing it only proves the number is well formed; the taxpayer search on the GST portal shows whether it is registered and active.
Under sections 7 and 8 of the IGST Act, 2017, a supply is intra-state when the supplier's location and the place of supply are in the same state, and inter-state when they are in different states.
| Supply | Tax charged | On an 18% item |
|---|---|---|
| Within one state | CGST + SGST, half each | 9% + 9% |
| Between two states | IGST at the full rate | 18% |
| Within a union territory without a legislature, such as Chandigarh | CGST + UTGST | 9% + 9% |
| Export, or supply to an SEZ unit | Treated as inter-state and zero-rated | IGST or none |
For goods, the place of supply is usually where delivery ends, and for most services to a registered business it is the buyer's location. So comparing the state codes of the two GSTINs gives the right answer in the common case, but not always. A buyer with no GSTIN can be in another state, a supply to an SEZ unit is inter-state even within the supplier's own state, and services such as work on a building or admission to an event take their place of supply from where the building or event is.
Each line carries a classification code: an HSN code for goods, from the World Customs Organization's Harmonized System, or a SAC (Services Accounting Code) for services. SAC codes all begin with 99: 9983 covers other professional, technical and business services, and 9987 maintenance, repair and installation.
The number of digits depends on turnover. Under Notification 78/2020–Central Tax, a business with aggregate turnover up to ₹5 crore in the previous financial year shows 4 digits on invoices to registered buyers and may leave the code off invoices to unregistered buyers. A business above ₹5 crore shows 6 digits on every tax invoice.
The rate follows from the code. Since 22 September 2025, most goods and services have been taxed at 5% or 18%, with 40% for a short list of luxury and sin goods, no tax on exempt supplies and special rates for a few items such as gold. Rates change by notification, so check the current rate for each code.
A consultancy in Karnataka (state code 29) bills a client registered in Karnataka. Both lines are taxed at 18%:
| # | Description | SAC | Qty | Rate (₹) | Discount (₹) | Taxable (₹) | CGST 9% (₹) | SGST 9% (₹) |
|---|---|---|---|---|---|---|---|---|
| 1 | Consulting services | 9983 | 1 | 25,000.00 | 0.00 | 25,000.00 | 2,250.00 | 2,250.00 |
| 2 | Laptop servicing | 9987 | 3 | 1,499.00 | 200.00 | 4,297.00 | 386.73 | 386.73 |
On line 2, 3 × 1,499 = ₹4,497. A discount recorded on the invoice at the time of supply reduces the taxable value under section 15 of the CGST Act, so the 18% is charged on ₹4,297: ₹773.46, in two halves of ₹386.73.
| Summary | ₹ |
|---|---|
| Taxable value | 29,297.00 |
| CGST | 2,636.73 |
| SGST | 2,636.73 |
| Round off | −0.46 |
| Total payable | 34,570.00 |
In words: Rupees Thirty Four Thousand Five Hundred Seventy Only. For a client registered in Maharashtra (27), the same lines would carry IGST of ₹4,500.00 and ₹773.46, ₹5,273.46 in all, and the total would still be ₹34,570.
Tax is usually worked out line by line to the paisa. When a line's tax is an odd number of paise, the halves cannot be equal: 5% of ₹105 is ₹5.25, so one half is ₹2.63 and the other ₹2.62. Many businesses also round the amount payable to the nearest rupee and show the difference on a round-off line, as in the example above.
Rates on an invoice are prices before tax. For a price that includes GST, divide by 1 plus the rate first: ₹1,180 including 18% GST is 1,180 ÷ 1.18 = ₹1,000 of taxable value and ₹180 of GST. Taking 18% off ₹1,180 gives the wrong ₹967.60. The percentage guide explains reverse percentages, and the remove mode of the VAT Calculator does the division at any rate.
A business whose aggregate annual turnover has crossed the e-invoicing threshold in any financial year since 2017-18 must upload each invoice to a registered business to an Invoice Registration Portal (IRP). The IRP returns an Invoice Reference Number (IRN) and a digitally signed QR code, which go on the invoice. The threshold started at ₹500 crore in October 2020 and was lowered in stages to ₹5 crore from 1 August 2023; check the current limit on the GST portal. For such a business, an invoice without an IRN is not treated as a valid invoice under rule 48 of the CGST Rules.
Every invoice also goes into the GSTR-1 return, and the GST Filing Prep tool groups a period's invoice rows into its B2B, B2CL, B2CS and rate-wise tables.
The GST Invoice Generator builds a tax invoice as a PDF. You enter the invoice number, date and place of supply, both parties' name, GSTIN, address and state, and one line per item with a description, HSN/SAC code, quantity, rate, a discount in rupees and a GST rate of 0, 3, 5, 12, 18, 28 or 40%. A GSTIN that fails the check is flagged but does not block the invoice.
It chooses between CGST + SGST and IGST by comparing the first two digits of the two GSTINs, treating the supply as intra-state when either is missing, or you can set the supply type by hand. Lines are priced as in the example, the total is rounded to the nearest rupee with a round-off line, and the amount is written in words using lakh and crore.
The PDF is a horizontal A4 page headed Tax Invoice, with supplier and recipient blocks, the item table, a tax summary by rate when lines use more than one rate, the totals, the amount in words, your notes, an authorised signatory line and the supplier's GSTIN in the footer. You preview it, then download it under the invoice number. Everything is calculated and drawn in your browser, and nothing is uploaded or saved.
There is no unit column, cess, reverse-charge field or UTGST label (the state half is always called SGST), and the rate menu covers 0, 3, 5, 12, 18, 28 and 40% but not other special rates such as 0.25%; a reverse-charge statement or export declaration can go in the notes. The date prints as year-month-day. The PDF uses built-in Latin fonts, so Hindi text and the ₹ sign are left out, with a warning. The tool does not number invoices, check the 16-character limit, create an IRN or file anything. Its figures are estimates based on what you enter, not tax advice.
What is the difference between CGST, SGST and IGST? CGST goes to the central government and SGST to the state; the two are charged together, half each, on a supply within one state. IGST is charged alone at the full rate on a supply between states. On an 18% item that is 9% + 9% or 18% IGST, the same total.
How do I calculate GST on an invoice? Multiply each line's taxable value (quantity × rate, less any discount shown on the invoice) by the GST rate. ₹25,000 at 18% is ₹4,500: ₹2,250 CGST and ₹2,250 SGST within a state, or ₹4,500 IGST between states.
How long can a GST invoice number be? Up to 16 characters, using letters, digits, hyphens and slashes, in a consecutive series that is unique within the financial year. Putting the year in a prefix, such as INV/26-27/001, keeps numbers unique when a new series starts in April.
Is e-invoicing mandatory for my business? Only if your aggregate turnover has crossed the threshold, ₹5 crore since 1 August 2023, in any financial year from 2017-18 on. The limit has been lowered several times, so check the GST portal.
Can I issue a tax invoice to an unregistered customer? Yes, without a recipient GSTIN; the name, address and state are required once the taxable value is ₹50,000 or more. In the generator, set the supply type by hand for a customer in another state, because automatic detection needs both GSTINs.
Can I add a UPI QR code to the invoice? The generator has no image field, so make the code with the UPI QR Code Generator, with the amount and the invoice number in the note, and send it with the PDF. The UPI QR guide explains what the code contains.
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