A GST tax invoice does two jobs. It records your sale and the tax you owe on it, and it is the document your buyer needs to claim input tax credit. If the invoice leaves out a required detail, the buyer's accountant will often hold the payment until you issue a corrected one. Rule 46 of the Central Goods and Services Tax Rules, 2017 sets out what every tax invoice must show.
01Who issues a tax invoice
Every registered person who makes a taxable supply issues a tax invoice under section 31 of the CGST Act. A composition dealer, or a business supplying only exempt goods or services, issues a bill of supply and does not charge tax on it.
For goods, the invoice is issued before or at the time the goods leave your premises. For services, it is issued within 30 days of the supply, and banks, insurers and NBFCs get 45 days.
02The particulars Rule 46 asks for
| Detail | What it means in practice |
|---|---|
| Your name, address and GSTIN | Exactly as on your registration certificate |
| Invoice number | Consecutive, up to 16 characters, unique for the financial year |
| Date of issue | The date the invoice is made |
| Buyer's name, address and GSTIN | For a registered buyer |
| Buyer's details for large B2C sales | Name, address, delivery address, state name and code, where the taxable value is ₹50,000 or more |
| HSN code for goods, SAC for services | 4 or 6 digits, depending on your turnover |
| Description of goods or services | Clear enough to identify what was sold |
| Quantity and unit | For goods, such as 200 boxes or 1,500 kg |
| Total value | Before any tax |
| Taxable value | After discounts that are allowed to be deducted |
| Rate and amount of tax | CGST and SGST, or IGST, shown separately, plus cess where it applies |
| Place of supply | With the state name, for inter-state supplies |
| Delivery address | Where it is different from the place of supply |
| Reverse charge | Whether tax is payable by the buyer under reverse charge |
| Signature | Your signature or digital signature, or that of an authorised person |
The invoice number can use letters, numerals, hyphens and slashes. A series such as MT/26-27/0142 has 13 characters and works well. Starting a new series on 1 April each year keeps numbers unique for the financial year without any extra effort.
HSN digits
Notification 78/2020-Central Tax, in force from 1 April 2021, sets the number of HSN digits. If your aggregate turnover in the previous financial year was up to ₹5 crore, you show 4 digits, and you may leave the HSN out on invoices to unregistered buyers. Above ₹5 crore, you show 6 digits on every invoice. The guide on HSN codes on invoices covers this in more detail.
03A worked example
A tile maker in Morbi sells 200 boxes of 600x600 mm vitrified tiles at ₹380 a box to a dealer in Ahmedabad. Both are in Gujarat, so the sale is intra-state and carries CGST and SGST.
| Line | Amount |
|---|---|
| 200 boxes vitrified tiles, HSN 6907, at ₹380 | ₹76,000 |
| CGST at 9% | ₹6,840 |
| SGST at 9% | ₹6,840 |
| Invoice total | ₹89,680 |
If the same order went to a dealer in Jaipur, the place of supply would be Rajasthan. The invoice would show IGST at 18%, which is ₹13,680, the same total of ₹89,680, and "Place of supply: Rajasthan (08)". The CGST, SGST and IGST guide explains the split.
The rate of 18% on ceramic tiles is the rate as of October 2026. Rates change by notification, so check the current rate for each HSN before you set up your item list.
04Other wording the rules require
Some invoices need a printed line in addition to the usual details.
- Exports under LUT
- The invoice carries the endorsement "SUPPLY MEANT FOR EXPORT/SUPPLY TO SEZ UNIT OR SEZ DEVELOPER FOR AUTHORISED OPERATIONS UNDER LETTER OF UNDERTAKING WITHOUT PAYMENT OF INTEGRATED TAX". It also shows the buyer's name, delivery address and the country of destination. See exporting without IGST.
- Reverse charge
- Where the buyer pays the tax, the invoice says so.
- Revised invoices
- An invoice issued to replace an earlier one is marked "Revised Invoice" and refers to the original.
05Copies and small sales
For goods, the invoice is made in triplicate: the original for the buyer, the duplicate for the transporter and the triplicate for you. For services, two copies are enough. Where an e-invoice has been generated, the transporter's duplicate copy is not needed.
For sales to unregistered buyers below ₹200, the law lets you skip an invoice for each sale if the buyer does not ask for one, and issue one consolidated invoice for such sales at the end of the day. A kirana counter or a tea stall usually works this way.
06Mistakes that cost the buyer credit
Most invoice problems are small, and most of them show up when the buyer's accountant matches your invoice against GSTR-2B.
- Wrong GSTIN of the buyer. The credit lands with someone else, or nowhere. Copy the GSTIN from the buyer's certificate or verify it on the GST portal.
- Wrong tax heads. Charging CGST and SGST on an inter-state sale, or IGST on a local one, means paying the right tax again and claiming a refund of the wrong one.
- A missing place of supply on an inter-state invoice.
- Duplicate invoice numbers after a system change or a second billing book.
- No HSN, or too few digits, once turnover has crossed ₹5 crore.
A corrected invoice, or a credit or debit note, fixes most of these. It is easier to get the details right when the invoice is made.
07E-invoicing for larger businesses
If your aggregate turnover crossed ₹5 crore in any financial year since 2017-18, B2B invoices must also be reported to the Invoice Registration Portal, which returns an IRN and a signed QR code. Rule 46 still decides what the invoice contains. The e-invoice guide explains who is covered.
This guide is general information as of October 2026 and does not amount to tax advice.
In MatruOS, a GST invoice carries the HSN code, the CGST and SGST or IGST split by state, the amount in words and a number from your series.