GST invoice format in India: the mandatory fields (2026 checklist)

A valid GST tax invoice in India must carry a specific set of fields — the supplier and buyer details with GSTINs, a unique invoice number and date, the HSN/SAC codes, the taxable value, and the CGST/SGST or IGST breakup. Miss one and the invoice can be treated as non-compliant, which affects your buyer's input tax credit. Here is the full list in plain English, plus a checklist you can reuse.

When you must issue a GST tax invoice

A registered supplier issues a tax invoice for a taxable supply of goods or services. For goods, it is issued on or before the removal/delivery; for services, generally within 30 days of supply. If you are not registered, or the supply is exempt, you issue a bill of supply instead of a tax invoice.

The mandatory fields

A compliant GST invoice generally includes:

1. Supplier name, address, and GSTIN.
2. A consecutive invoice number — unique for the financial year, up to 16 characters.
3. Date of issue.
4. Buyer name, address, and GSTIN (if the buyer is registered).
5. Place of supply and the state code — this decides CGST+SGST vs IGST.
6. Shipping address, if different from the place of supply.
7. HSN code (goods) or SAC code (services) for each line.
8. Description, quantity, and unit for each item.
9. Taxable value and any discount.
10. GST rate and amount, split as CGST + SGST (intra-state) or IGST (inter-state).
11. Whether tax is payable on reverse charge, where applicable.
12. Signature or digital signature of the supplier or an authorised person.

For an unregistered buyer, name and address are still recommended above a certain invoice value.

If you are unsure how the tax splits, our guide to CGST, SGST and IGST walks through worked examples.

HSN/SAC codes: how many digits?

The number of HSN digits you must show depends on your turnover, and the requirement has tightened over time — check the current rule for your turnover band. If you are not sure which code applies, see what an HSN code is and how to find yours.

A copy-ready checklist

Before you send an invoice, confirm it has:

• Your GSTIN and the buyer's GSTIN (for B2B)
• A unique, sequential invoice number and date
• Place of supply and state code
• HSN/SAC on every line
• Correct CGST+SGST or IGST split
• Taxable value, tax amount, and grand total
• Reverse-charge note if applicable
• Signature / digital signature

Let software enforce the format

The reliable way to never miss a field is to use billing software that builds the GST format for you. Invoicify fills the tax breakup, HSN/SAC, and place-of-supply logic automatically, so every invoice comes out compliant. You can start a free trial and issue your first GST invoice in minutes.

Getting the format right is mostly a one-time setup: once your template and product list carry the right codes, every future invoice inherits them.