A clean invoice gets paid faster. For a GST-registered business it is also a legal document: your buyer claims input tax credit on it, and errors can hold up both the payment and their credit. This checklist covers the fields most small businesses need, based on the invoice rules under the CGST Rules. It is general guidance, not tax advice, so confirm specifics with your CA.

Fields a tax invoice should carry

  • Your name, address and GSTIN as the supplier.
  • A consecutive invoice number, unique for the financial year, of up to 16 characters (letters, numbers, hyphen or slash).
  • The invoice date.
  • The buyer's name and address, and the buyer's GSTIN if they are registered.
  • HSN code for goods or SAC code for services, at the number of digits that applies to your turnover.
  • A description of the goods or services, quantity and unit, and the total value.
  • Taxable value after any discount.
  • GST rate and amount, split as CGST and SGST, or as IGST.
  • Place of supply, with the state name, for inter-state supplies.
  • Whether tax is payable on reverse charge.
  • Your signature or digital signature, or that of an authorised representative.

CGST and SGST, or IGST?

The split depends on where the supply happens relative to where you are registered. When the supplier's location and the place of supply are in the same state or union territory, the supply is intra-state and you charge CGST plus SGST (or UTGST), each at half the rate. When they are in different states, it is inter-state and you charge IGST at the full rate.

For services, the place of supply rules can be less obvious than for goods, especially for online or cross-border services. If you are unsure, ask your CA before you issue the first invoice to a new kind of client, because correcting tax type later means credit notes and fresh invoices.

Mistakes that slow down payment

  • A wrong or mistyped buyer GSTIN, which can stop the buyer from claiming credit.
  • Charging IGST on an intra-state sale, or CGST and SGST on an inter-state one.
  • Gaps or repeats in invoice numbering.
  • Missing HSN or SAC codes.
  • No bank or UPI details, so the buyer has to ask how to pay.

When you are not registered

A business that is not registered for GST cannot charge GST. A registered business that supplies exempt goods or services, or that has opted for the composition scheme, issues a bill of supply instead of a tax invoice. A bill of supply carries no tax lines.

Draft one privately in your browser

Productive IT's free GST Invoice Utility builds a tax invoice PDF with CGST and SGST or IGST, checks the GSTIN format and checksum, writes the amount in words, and switches to a bill of supply when you untick the registered seller box. Line items are never uploaded.

Open the GST Invoice Utility → · Browse free calculators →

Frequently asked questions

Is HSN code mandatory on a GST invoice?

Yes for most registered businesses. The number of digits depends on annual turnover and whether the sale is B2B or B2C, so confirm the applicable rule with your CA.

When should I charge IGST instead of CGST and SGST?

Charge IGST when the supplier's location and the place of supply are in different states or union territories. Charge CGST and SGST when they are in the same state.

How long can a GST invoice number be?

Up to 16 characters, using letters, numbers, hyphens or slashes, and it must be unique within the financial year.

Is the Productive IT GST invoice tool free?

Yes. It works without an account, and the free plan covers four PDFs per IST calendar month.

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