A GST invoice is more than a bill. It is the document your customer uses to claim input tax credit, the record your return is built from and the first thing an officer asks for. Here is what it must contain, with a real example.
When you must issue a tax invoice
A registered person making a taxable supply issues a tax invoice. If the supply is exempt or you are under the composition scheme, you issue a bill of supply instead, with no GST charged. Timing matters:
| Supply | Issue the invoice |
|---|---|
| Goods | Before or at the time of removal or delivery of the goods |
| Services | Within 30 days of supplying the service |
| Continuous supply of goods | Before or at the time each statement or payment is due |
The mandatory fields (Rule 46)
The CGST Rules list what a tax invoice must show. In practice, check every bill for these:
- Your name, address and GSTIN
- A consecutive invoice number, unique for the financial year, up to 16 characters (letters, numbers, "-" and "/")
- Date of issue
- Customer name, address and GSTIN if registered
- For an unregistered customer with invoice value of Rs 50,000 or more: name, address and delivery address with state
- HSN code for goods or SAC for services (4 digits up to Rs 5 crore turnover for B2B, 6 digits above that)
- Description, quantity and unit
- Total value, discount and taxable value
- GST rate and amount for each tax: CGST, SGST/UTGST or IGST, and cess
- Place of supply with the state name, for inter-state supplies
- Delivery address, if different from the place of supply
- Whether tax is payable on reverse charge
- Signature or digital signature of the supplier
How many copies?
For goods, prepare three: Original for recipient, Duplicate for transporter and Triplicate for supplier. For services, two: original for the recipient and duplicate for the supplier. Good billing software prints the copy label for you.
Working out the tax
The GST rate comes from the HSN/SAC of the item. Whether that rate is split into CGST + SGST or charged as IGST depends on the place of supply. Since 22 September 2025, most goods and services fall in the 5% or 18% slab, with 40% for a small list of luxury and sin goods and a few special rates. Check the rate for each HSN when you set up your products.
Example from the invoice above, a sale within Delhi:
| Item | Taxable value | GST | CGST 9% | SGST 9% | Total |
|---|---|---|---|---|---|
| Ceiling Fan 1200 mm × 11 | 25,850.00 | 18% | 2,326.50 | 2,326.50 | 30,503.00 |
| PVC Conduit Pipe 25 mm × 18 m | 684.00 | 18% | 61.56 | 61.56 | 807.12 |
| Invoice total | 26,534.00 | 2,388.06 | 2,388.06 | 31,310.12 |
Creating it in billing software, step by step
- Pick the document type: tax invoice, bill of supply, quotation and so on.
- Select or add the customer. A valid GSTIN fills the state and PAN.
- Check the place of supply. It decides CGST + SGST or IGST.
- Add items. HSN, unit and GST rate come from your product list.
- Add discounts, freight or TDS/TCS if needed.
- Save. The number is assigned from the series, and stock and ledgers update.
- Print, download the PDF or share it on WhatsApp.
Common mistakes that cost ITC or invite notices
- Wrong or inactive customer GSTIN: your customer loses the credit.
- CGST + SGST charged on an inter-state sale (or the reverse): the wrong tax has to be paid again and the other claimed back.
- Skipped or repeated invoice numbers: they show up in the Documents Issued table of GSTR-1.
- Missing HSN or too few digits for your turnover.
- Tax charged on the MRP instead of the transaction value.
- Editing a filed invoice instead of issuing a credit or debit note.
What about e-invoicing?
If your aggregate turnover in any financial year since 2017-18 crossed Rs 5 crore, B2B invoices must also be reported to the Invoice Registration Portal (IRP) to get an IRN and signed QR code. Businesses with turnover of Rs 10 crore or more must report each invoice within 30 days of its date. Below Rs 5 crore, a correctly formatted tax invoice like the one above is enough.
📌 GST law changes often. This guide reflects the rules as we understand them in October 2026. Confirm anything specific to your business with your CA or on gst.gov.in.
Software for this: NexoraGST GST Billing Software · for small business · in Delhi
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