This guide summarises the tax invoice rules under the CGST Rules for everyday small-business use. Rules change and special cases exist (exports, e-invoicing, composition dealers), so confirm with your CA for your situation.
Download a free GST invoice template
GST invoice format in Excel.xlsx · CGST/SGST or IGST formulas
GST invoice format in Word.docx · edit and save as PDF
Mandatory fields on a GST tax invoice
- Supplier's name, address and GSTIN.
- A consecutive invoice number, unique for the financial year, up to 16 characters (letters, numbers, "-" and "/"), for example INV/26-27/0107.
- Date of issue.
- Recipient's name and address, and their GSTIN if registered.
- For unregistered recipients with a taxable value of ₹50,000 or more: name, address, and the delivery address with state name and code.
- HSN code for goods or SAC code for services.
- Description, quantity and unit of goods or services.
- Total value, and the taxable value after any discount or abatement.
- Tax rate and amount: CGST, SGST/UTGST, IGST and cess, shown separately.
- Place of supply, with 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 or authorised representative.
How many HSN/SAC digits?
| Turnover in the previous year | HSN/SAC digits on invoices |
|---|---|
| Up to ₹5 crore | 4 digits on B2B invoices (optional on B2C) |
| More than ₹5 crore | 6 digits on all invoices |
Sample GST invoice (inter-state, IGST)
A Chennai business billing a Bengaluru customer: different states, so the whole 18% is IGST and the place of supply is Karnataka.
TAX INVOICE
No. INV/26-27/0107Date: 13 Oct 2026
Place of supply: Karnataka (29)
Arun Web Studio
Anna Nagar, Chennai, Tamil Nadu
GSTIN 33ABCDE1234F1Z5
Anna Nagar, Chennai, Tamil Nadu
GSTIN 33ABCDE1234F1Z5
Bill toNova Retail LLP
Indiranagar, Bengaluru, Karnataka
GSTIN 29PQRSX5678K1Z2
Indiranagar, Bengaluru, Karnataka
GSTIN 29PQRSX5678K1Z2
DetailsDue 27 Oct 2026
Reverse charge: No
Reverse charge: No
| Description | HSN/SAC | Qty | Rate | Amount |
|---|---|---|---|---|
| UI/UX design (5 pages) | 998314 | 1 job | ₹35,000.00 | ₹35,000.00 |
| Website development with CMS | 998314 | 1 job | ₹80,000.00 | ₹80,000.00 |
| Hosting & domain, 1 year | 998315 | 1 year | ₹10,000.00 | ₹10,000.00 |
Taxable value₹1,25,000.00
IGST 18%₹22,500.00
Total₹1,47,500.00
Amount in words: Rupees One Lakh Forty-Seven Thousand Five Hundred Only.
Pay to: Bank account and UPI ID shown here · Authorised signatory
Pay to: Bank account and UPI ID shown here · Authorised signatory
Invoice numbering tips
- Restart the series each financial year (April to March) and include the year, such as INV/26-27/0001.
- Never skip or reuse a number. If an invoice is wrong, issue a credit note rather than deleting it.
- Use separate series for different document types if you like (QT for quotes, INV for invoices).
Make GST invoices automatically
CappsAI Studio is a free GST invoice generator. Add your GSTIN and your customer's once; Studio prints both, adds HSN/SAC codes from your saved services, works out CGST + SGST or IGST from the two states, sets the place of supply, numbers invoices with your own prefix, and tracks what's paid and overdue. It also handles recurring invoices for retainers and AMCs.