GST Invoice Format in India (2026): Rules, Fields & Free Template

Getting your GST invoice format right matters for one big reason: it's what allows your buyer to claim input tax credit and keeps you on the right side of the GST law. This guide covers the exact format prescribed under the CGST Rules, the mandatory fields, and how to generate a compliant invoice for free.

Tax invoice vs bill of supply

A tax invoice is issued by a GST-registered supplier for taxable goods or services and shows the GST charged. A bill of supply is issued when GST can't be charged — for example by a composition-scheme dealer or for exempt supplies. If you're registered and charging GST, you'll almost always issue a tax invoice.

Mandatory fields in the GST invoice format

As per the CGST Rules, a compliant tax invoice must contain:

• Supplier's name, address and GSTIN
• A consecutive invoice number (unique for the financial year) and date of issue
• Recipient's name, address and GSTIN (or state name + code for unregistered buyers where value exceeds ₹50,000)
• HSN code for goods or SAC code for services
• Description, quantity, unit and total value of goods/services
• Taxable value, discount, and the GST rate
• Amount of tax — CGST + SGST/UTGST for intra-state, or IGST for inter-state
• Place of supply (and delivery address if different)
• Whether GST is payable on reverse charge
• Signature or digital signature of the supplier

How many copies and when to issue

For goods, prepare the invoice in triplicate (original for recipient, duplicate for transporter, triplicate for supplier). For services, duplicate is enough. Time limits: for goods, issue on or before removal/delivery; for services, within 30 days of supply.

HSN/SAC digit requirements

The number of HSN digits you must quote depends on turnover — typically 4 digits for smaller businesses and 6 digits above the prescribed threshold. When you enter HSN codes on your line items, a good tool also rolls them up into your GSTR-1 HSN summary automatically.

Free GST invoice template — the fastest way

Instead of copying a Word or Excel template and maintaining tax formulas by hand (see our templates vs generator comparison), use a free GST invoice generator. Set up your GSTIN once, pick the place of supply, and CGST/SGST or IGST is filled in for you — in the correct format, every time.

For the full walkthrough, see our step-by-step guide on how to create a GST invoice online. Official field definitions are on the GST portal.