GST Invoice Format: Mandatory Fields and Sample

There's no government-issued GST invoice template. You can design your own, but Rule 46 of the CGST Rules lists what it must contain: your name, address and GSTIN, a unique serial number, the date, your buyer's details, HSN code, item details, taxable value, tax rate and amount, place of supply, and a signature. The checklist below goes through each one.

Mandatory fields on a GST tax invoice

A sample GST invoice layout

This is a sample. Check the rate and HSN for your own items.

TAX INVOICE

Sharma Traders                       Invoice No: ST/26-27/0142
12 MI Road, Jaipur, Rajasthan        Date: 31 Oct 2026
GSTIN: 08AAAAA0000A1Z5               Place of supply: Rajasthan (08)
                                     Reverse charge: No
Bill to:
Gupta Hardware
45 Station Road, Ajmer, Rajasthan
GSTIN: 08BBBBB0000B1Z5

Item              HSN    Qty  Rate    Taxable  CGST 9%  SGST 9%
PVC Pipe 1 inch   3917   50   200.00  10,000   900      900

Taxable value                  10,000.00
CGST @ 9%                         900.00
SGST @ 9%                         900.00
Invoice total                  11,800.00
Rupees eleven thousand eight hundred only

Authorised signatory

Notice the split. The seller and place of supply are both in Rajasthan, so this is an intra-State sale with CGST and SGST. If the buyer's place of supply were another state, it would show IGST instead.

How many HSN digits do you need?

Under Notification 78/2020-Central Tax, it depends on your turnover in the previous financial year:

What if the buyer isn't registered?

For a sale to an unregistered buyer, Rule 46 requires the name, address, delivery address, State and State code when the taxable value is ₹50,000 or more. Below that, you need to show these only if the buyer asks.

The rules for your invoice number

The number must be consecutive and unique for each financial year. Common formats:

• ST/26-27/0142
• INV-0142

Avoid changing formats in the middle of the year. A separate series is often used for different branches or document types. Discuss this with your CA.

When to issue the invoice

How many copies?

Under Rule 48:

• Goods: three copies, marked Original for Recipient, Duplicate for Transporter and Triplicate for Supplier.
• Services: two copies, marked Original for Recipient and Duplicate for Supplier.
• E-invoices: this copy rule doesn't apply.

Tax invoice or bill of supply?

Use a bill of supply instead of a tax invoice when you can't charge tax, such as exempt goods or services, or if you're a composition taxpayer. Rule 49 sets out what it must contain. If you sell both taxable and exempt items to an unregistered buyer, a single combined document is allowed under Rule 46A.

Corrections are made through credit notes and debit notes, not by editing an issued invoice. Ask your CA how to issue them for your case.

Mistakes that cause trouble

1. Wrong GSTIN on the buyer's details. Your buyer may not see the tax credit. Check the GSTIN on the GST portal before saving a new buyer.
2. Wrong place of supply. It decides CGST/SGST or IGST, and fixing it later is painful.
3. Gaps or duplicates in numbering. Keep a clean series and reset it properly each financial year.
4. Missing or short HSN codes, given the turnover rule above.
5. Rounding that doesn't match. Calculate tax per line consistently.
6. Discount not shown clearly, so the taxable value looks wrong.
7. Typing tax rates by hand. One wrong entry repeats on every invoice. Save each rate against the item.

For tax rates: from 22 September 2025, the main slabs are 5% and 18%, with 40% for select goods and services. Some tobacco items follow a separate transition. Always confirm your item's rate from the official list or with your CA.

When is an e-invoice required?

If your aggregate turnover in any financial year from 2017-18 onward crossed ₹5 crore, you generally need to generate e-invoices for B2B supplies. Our guide on e-invoice vs e-way bill explains who needs what.

How KhataBhai handles this

You save the HSN and GST rate on each item once. On a KhataBhai invoice:

• Your GSTIN, address and HSN are shown when GST is on, and you can choose Place of Supply and Reverse Charge Applicable on the web invoice form.
• CGST, SGST or IGST is split for you by rate.
• Invoice numbers follow your Invoice prefix and Start number, and restart each financial year.
• You can add a signature, which prints as Authorized Signatory, and an optional UPI QR code.
• Credit Notes handle corrections and returns.

Your GST reports, including the GSTR-1 Register and GSTR-3B Summary, are ready to download for your CA. KhataBhai doesn't file returns for you, and you should still have your CA check your invoice setup.

A sample invoices screen, shown with demo data.

See billing and GST in KhataBhai. If you also sell online, an order from your Online Store becomes this same invoice once you accept it.

Frequently asked questions

Can I make a GST invoice in Excel or Word?

Yes, if it carries all the required details. The format isn't fixed. The risk is in manual mistakes in numbering, tax and HSN codes, and in the extra work of keeping your records for returns.

Is a signature mandatory on a GST invoice?

The rule requires a signature or digital signature, but an electronic invoice issued under the Information Technology Act doesn't need one. For a printed invoice, sign or stamp it.

What's the maximum length of an invoice number?

Up to 16 characters, using letters, numbers, hyphens or slashes.

Is a GST invoice needed for every sale?

A registered person supplying taxable goods or services generally issues a tax invoice, but there are specific cases, including a small-value consolidated option for certain sales to unregistered buyers. Confirm with your CA.