Tax Invoice Format: GST Tax Invoice Fields, Rules & Free Generator

A GST-registered business is legally required to issue a tax invoice for every taxable supply of goods or services. Not just any invoice — a tax invoice with specific fields that the GST law prescribes. An invoice that misses any mandatory field isn’t just poorly formatted, it’s non-compliant, and the buyer may lose their right to claim input tax credit against it.

The generator below creates a compliant tax invoice. This page explains exactly what the rules require and why each field matters.

The mandatory fields on a GST tax invoice

Rule 46 of the CGST Rules prescribes what must appear on every tax invoice. For B2B supplies (where the buyer is GST-registered), all of these are required:

1. Name, address, and GSTIN of the supplier
2. A unique, consecutive invoice number — not more than 16 characters, can include letters, numbers, and special characters. The numbering can restart each financial year but must be sequential within a series
3. Date of issue
4. Name, address, and GSTIN of the recipient (the buyer, if registered)
5. Name and address of the delivery location (if delivery is to a different location than the billing address)
6. HSN code for goods, or SAC code for services — 2 digits for turnover up to ₹5 crore, 4 digits for ₹5–50 crore, 6 digits for above ₹50 crore
7. Description of goods or services
8. Quantity (and unit of measurement for goods)
9. Total value of the supply
10. Taxable value (value after deducting any discount, on which tax is calculated)
11. Rate of tax (CGST + SGST or IGST percentage)
12. Amount of tax — shown separately: CGST amount, SGST/UTGST amount, or IGST amount
13. Place of supply (state name and code) — determines whether CGST+SGST or IGST applies
14. Address of delivery if different from place of supply
15. Whether the supply is taxable on a reverse charge basis (if applicable)
16. Signature or digital signature of the supplier or their authorised representative

CGST + SGST vs IGST: how the place of supply decides

The place of supply is the most practically important field because it determines which tax applies.

Same state (intra-state supply): Supplier and buyer are in the same state. Tax splits as CGST (central) + SGST (state), each at half the total rate. An 18% transaction becomes 9% CGST + 9% SGST. Both are shown as separate line items.

Different states (inter-state supply): Supplier and buyer are in different states. The full rate applies as IGST (integrated tax). An 18% transaction shows as 18% IGST, no split.

Getting this wrong — charging CGST+SGST on an inter-state transaction — is a common error that makes the invoice non-compliant. The buyer can’t claim ITC on CGST+SGST paid for an inter-state supply.

B2B vs B2C tax invoice differences

B2B (buyer is GST-registered): All 16 fields above are required. The buyer’s GSTIN must appear. This invoice is the basis for the buyer’s ITC claim, so it goes into GSTR-1 and flows to GSTR-2B.

B2C large (unregistered buyer, value above ₹2.5 lakh for inter-state or above ₹50,000 for some states): No buyer GSTIN (they don’t have one). Place of supply is essential. These invoices must be uploaded to GSTR-1 individually.

B2C small (unregistered buyer, value below ₹50,000): Buyer name and address aren’t mandatory. A simplified format is allowed. These are reported as a consolidated figure in GSTR-1, not uploaded individually.

Time limit to issue a tax invoice

For goods: the invoice must be issued at the time of removal (when goods leave the supplier’s premises) or delivery to the buyer, whichever is earlier.

For services: the invoice must be issued within 30 days of the date of supply of service. For banks and financial institutions, the limit is 45 days.

Issuing an invoice after these limits doesn’t make the supply non-taxable — GST is still owed — but it’s a compliance violation that can attract a penalty.

Discount on a tax invoice

Discounts given at the time of supply (shown on the invoice) reduce the taxable value before tax is calculated. A 10% discount on ₹1,00,000 means tax is calculated on ₹90,000.

Post-supply discounts (agreed after the invoice is already raised) cannot reduce the taxable value on that invoice. They require a credit note. The GST Act specifically disallows treating post-supply discounts as a deduction on the original invoice.

Related: GST invoice template to generate the invoice directly, e-invoice GST if your turnover exceeds ₹5 crore, and credit note template for post-supply adjustments.