What to Include on a GST Invoice: Checklist for Small Businesses

Why the invoice details matter

For a registered business, a tax invoice is more than a bill. Your customer may use it to claim input tax credit, and you need it to report the sale correctly in your returns. If important details are missing or wrong, a business customer may ask you to reissue the invoice, and payments can get delayed while that is sorted out.

This guide is a practical checklist based on the common requirements for a tax invoice. It is general information, not tax advice. GST rules and invoice formats can change, and some details depend on your type of business and turnover, so confirm the current requirements with a chartered accountant or on the official GST portal before you finalise your invoice format.

Seller and buyer details

The top part of the invoice identifies who is selling and who is buying. Getting these right is the first thing a business customer’s accountant will check.

• Your legal business name, address and GSTIN
• The words Tax Invoice clearly at the top
• Buyer’s name and address
• Buyer’s GSTIN, if the buyer is registered under GST
• For an unregistered buyer in some cases, the delivery address and state name and code may still be needed

Invoice number, date and place of supply

Each invoice needs a serial number that is unique within the financial year and runs in order. Many small businesses use a simple pattern such as 2026-27/045, which resets each April. Do not skip numbers or reuse a number for a corrected invoice; ask your accountant how to handle corrections properly.

The invoice date should be the actual date of issue. Place of supply is the state where the supply is treated as made, and it decides whether you charge CGST and SGST or IGST. It is especially important on inter-state invoices, so write the state name and its code.

Item lines: HSN or SAC, value and tax

Every line of the invoice should describe what you supplied and show how the tax was worked out.

• Description of goods or services, clear enough for someone else to understand
• HSN code for goods or SAC code for services; how many digits you must show can depend on your turnover, so check the current rule
• Quantity and unit for goods, such as pieces, kg or metres
• Rate per unit and total value, then any discount
• Taxable value, which is the value after discount on which GST is charged
• GST rate and amount, shown as CGST and SGST for an intra-state supply or IGST for an inter-state supply
• Invoice total in figures and in words
• Whether tax is payable on reverse charge, where that applies
• Signature or digital signature of the supplier or an authorised person

A worked example

Suppose Neha, a freelance graphic designer registered under GST in Pune, Maharashtra, does two jobs for a client. For this example, assume the applicable GST rate on her service is 18 percent; you must check the correct rate for your own goods or services.

Line 1: Logo design, ₹12,000. Line 2: Brochure design, ₹8,000. Taxable value = ₹20,000. GST at 18 percent = 20,000 x 18 / 100 = ₹3,600.

If the client is in Mumbai, also in Maharashtra, it is an intra-state supply. The invoice shows CGST at 9 percent, ₹1,800, and SGST at 9 percent, ₹1,800. Invoice total = ₹23,600, written in words as Rupees Twenty-Three Thousand Six Hundred Only. Place of supply: Maharashtra.

If the same work is billed to a client in Bengaluru, the place of supply would normally be Karnataka, which makes it an inter-state supply. The invoice then shows a single IGST at 18 percent, ₹3,600, and the total is still ₹23,600. The tax amount is the same; only the type of tax changes. Place of supply rules for services have special cases, so confirm them if you are unsure.

The Filyzo GST Calculator is handy for checking these figures. Enter the taxable value, choose 18 percent and Add GST to see the GST, the CGST and SGST halves and the total. If a customer agreed a price that already includes GST, use Remove GST to find the taxable value to show on the invoice.

Making a clean invoice template

If you do not use billing software yet, you can build a simple invoice template in the Filyzo Document Editor. Put your business details at the top, insert a table for the item lines, and add rows below it for taxable value, CGST, SGST or IGST and the total. Download it as Word (.docx) so you can reuse it, and use Download PDF to send each finished invoice to the customer.

Before sending any invoice, check this short list: the invoice number follows the previous one, the buyer’s GSTIN is typed correctly, the place of supply matches the tax type, the total in words matches the figure, and the invoice is signed. Keep a copy of every invoice you issue in a folder for each financial year. If your turnover grows, ask your accountant whether e-invoicing or other requirements now apply to you.