A GST invoice is a legal document, and what it must contain is set by CGST Rule 46. Get the fields right and your customer can claim input tax credit and your books stay clean. Get them wrong and you invite queries at filing time. This guide lists what belongs on a GST invoice, shows a sample layout, and shows how to make one free.
The mandatory fields on a GST invoice
Under CGST Rule 46, a tax invoice issued by a registered person must show all of the following.
| Field | What it must show |
|---|---|
| Supplier details | Your business name, address and GSTIN. |
| Invoice number | A unique serial for the financial year, up to 16 characters. |
| Invoice date | The date the invoice is issued. |
| Customer details | Name and address, plus GSTIN if they are registered. |
| Place of supply | The state, which decides CGST and SGST versus IGST. |
| HSN or SAC code | For each item of goods or service. |
| Description, quantity and unit | For each line. |
| Taxable value | After any discount. |
| GST rate and amount | Split into CGST and SGST, or IGST. |
| Whether tax is on reverse charge | If it applies. |
| Total amount | In figures, often also in words. |
| Signature | Of the supplier or an authorised person, physical or digital. |
A sample GST invoice layout
The same fields on an invoice for a same-state sale at 18% GST, laid out the way Apna Invoice prints it.
Sharma Traders
Shop 14, Laxmi Road, Pune 411030
GSTIN 27AAKFS4512M1Z3
TAX INVOICE
Original for recipient
No. INV/2026-27/0042
Date: 14 Nov 2026
Billed to
Kulkarni Infotech Pvt Ltd
Baner, Pune 411045
GSTIN 27AABCK7781Q1ZP
Place of supply
Maharashtra (27)
Reverse charge: No
| Description of goods / services | HSN/SAC | Qty | Rate | GST | Taxable value |
|---|---|---|---|---|---|
| Dell Latitude 3540 laptop | 8471 | 2 Nos | 45,000 | 18% | 90,000 |
| HP LaserJet printer | 8443 | 1 Nos | 10,000 | 18% | 10,000 |
Amount in words (INR)
Rupees One Lakh Eighteen Thousand Only
- Taxable value
- ₹1,00,000
- CGST @ 9%
- ₹9,000
- SGST @ 9%
- ₹9,000
- Grand Total
- ₹1,18,000
Authorised signatory
How to make a GST invoice in five steps
-
Add your business details and the customer's details, including GSTINs where they exist.
-
Give the invoice a unique number for the financial year, and the date of supply.
-
List each item with its HSN or SAC code, quantity, rate and taxable value.
-
Apply the correct split. Same state is CGST and SGST. Different state is IGST.
-
Show the grand total and add your signature.
Make a GST invoice free
With Apna Invoice you pick the customer, add the items, and the GSTIN, place of supply, CGST, SGST and IGST split and HSN or SAC fields are handled for you. You get a compliant PDF, ready to share on WhatsApp. Create your first GST invoice free, or try the free GST calculator first.
Frequently asked questions
What fields are mandatory on a GST invoice?
Under CGST Rule 46 a tax invoice must show the supplier name, address and GSTIN, a unique invoice number and date, the customer details, HSN or SAC codes, the taxable value, the GST rate and amount split into CGST and SGST or IGST, the place of supply for inter-state sales, and the signature of the supplier.
Is HSN code mandatory on every invoice?
HSN for goods and SAC for services is required when either party is GST registered. The number of digits depends on turnover. For sales between two unregistered parties it is not strictly required, though it is good practice.
When do I charge CGST and SGST versus IGST?
When the supplier and the place of supply are in the same state, you charge CGST and SGST. When they are in different states, you charge IGST. The total tax is the same, only the split changes.
What is the difference between a proforma invoice and a GST tax invoice?
A proforma invoice is a pre-sale quote sent before a deal is confirmed. It carries no GST liability and gives the buyer no input tax credit. The tax invoice under CGST Rule 46 is the legal document raised once the supply happens, and it is what fixes your GST liability and the buyer's ITC.
Do I need to generate an e-invoice (IRN) for my invoices?
E-invoicing, where each invoice gets an IRN and QR code from the government portal, applies only to businesses above the notified aggregate-turnover threshold (currently Rs 5 crore; always confirm the latest notification). Below that limit a normal Rule 46 tax invoice, like the format described here, is sufficient.
Can I make a GST invoice for free?
Yes. You can create a fully GST-compliant invoice free with Apna Invoice. The CGST, SGST and IGST split, HSN and SAC fields and a clean PDF are handled for you.
