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GST Invoice Format: Mandatory Fields Under Rule 46 (With Checklist)

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Quick answer

A GST tax invoice must show the supplier's name, address and GSTIN; a unique serial number of up to 16 characters for the financial year; the date; the recipient's name, address and GSTIN (if registered); the HSN or SAC code; a description, quantity and value of the goods or services; the taxable value; the GST rate and amount split into CGST and SGST/UTGST or IGST; the place of supply for inter-state supplies; whether tax is payable on reverse charge; and the supplier's signature. These requirements come from Rule 46 of the CGST Rules, 2017.

Mandatory fields on a GST tax invoice

Rule 46 of the CGST Rules, 2017 lists what a registered supplier’s tax invoice must contain. In practice that means:

FieldWhat to show
Supplier detailsName, address and GSTIN of the supplier.
Invoice numberA consecutive serial number of at most 16 characters (letters, digits, “-” and “/”), unique for the financial year.
Invoice dateDate of issue.
Recipient detailsName, address and GSTIN/UIN if the recipient is registered.
Unregistered recipient (₹50,000 or more)Name and address of the recipient and the delivery address, with the state name and state code.
HSN / SAC codeHSN code for goods, SAC for services (the number of digits depends on turnover — check the current CBIC notification).
Description, quantity, unitWhat was supplied and how much.
ValueTotal value and the taxable value after discounts.
Tax rate and amountRate and amount of CGST and SGST/UTGST, or IGST (and cess, if any).
Place of supplyState name — required for inter-state supplies.
Delivery addressIf it differs from the place of supply.
Reverse chargeWhether tax is payable on reverse charge basis.
SignatureSignature or digital signature of the supplier or an authorised representative.

A computer-generated invoice can carry a printed name in the signature block. Invoice Studio adds every one of these fields — fill them in once in your free GST invoice and they’re laid out correctly on every template.

Invoice number rules

The serial number must be unique for a financial year (April–March), consecutive, and no longer than 16 characters. Only letters, digits, hyphens (-) and slashes (/) are allowed. You may run more than one series — for example one per branch or one for exports.

  • INV/26-27/001 — prefix, financial year and running number (12 characters).
  • EXP-26-27-001 — a separate series for export invoices.

Invoice Studio lets you set a numbering pattern per document type, including the financial year and a running number.

When to issue and how many copies

GoodsServices
When to issueBefore or at the time of removal / delivery of goods.Within 30 days of supplying the service (Rule 47).
Copies (Rule 48)Three: original for recipient, duplicate for transporter, triplicate for supplier.Two: original for recipient, duplicate for supplier.

Mark copies as “Original for recipient”, “Duplicate for transporter” and so on when you print them.

What about e-invoicing (IRN)?

Businesses whose aggregate turnover is above the notified threshold must also register B2B invoices on the Invoice Registration Portal (IRP) to get an IRN and a signed QR code. Check the current threshold on the GST portal. Invoice Studio creates regular PDF tax invoices — it does not generate IRNs.

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Frequently asked questions

A GST invoice must include the supplier's name, address and GSTIN, a unique invoice number (max 16 characters), date, recipient details, HSN/SAC code, description, quantity, taxable value, GST rate and amount (CGST + SGST/UTGST or IGST), place of supply for inter-state supplies, reverse-charge status and the supplier's signature, as required by Rule 46 of the CGST Rules, 2017.

At most 16 characters. It can contain letters, digits, hyphens and slashes, must be consecutive, and must be unique for the financial year.

Yes. A tax invoice must carry the signature or digital signature of the supplier or an authorised representative. Computer-generated invoices commonly show the authorised signatory's name.

For goods, three copies — original for the recipient, duplicate for the transporter and triplicate for the supplier. For services, two copies — original for the recipient and duplicate for the supplier (Rule 48).

A tax invoice for services should be issued within 30 days from the date of supply of the service (Rule 47).

This guide is general information based on the CGST Rules, 2017 and the IGST Act, 2017. It is not tax or legal advice — rates, thresholds and notifications change, so confirm your situation with a chartered accountant or on the official GST portal (gst.gov.in / cbic.gov.in).