How to Write a GST Invoice in Australia (Step by Step)

If you run a business in Australia and are registered for GST, you are required to provide your clients with a proper tax invoice. Getting this wrong can cause problems for your clients when they try to claim GST credits — and it reflects poorly on your business.

The good news is that writing a correct GST invoice is straightforward once you know what the Australian Taxation Office (ATO) requires. This guide walks you through every step.

What is a GST Invoice?

A GST invoice — formally called a tax invoice — is a document you give to a customer when you sell goods or services and the sale includes GST (Goods and Services Tax). GST is a 10% tax added to most goods and services sold in Australia.

If your business is registered for GST and the sale is over $82.50 (including GST), you must provide a tax invoice if your customer asks for one. Most businesses provide one automatically for every sale.

A regular invoice and a tax invoice are different things. A tax invoice must meet specific ATO requirements. A regular invoice does not include GST details and is used by businesses not registered for GST.

Who Needs to Issue a GST Invoice?

You must issue tax invoices if your business is registered for GST, the sale amount is $82.50 or more (including GST), and your customer requests a tax invoice within 28 days of the sale.

You must register for GST if your business turnover is $75,000 or more per year. Sole traders, freelancers, and small businesses under this threshold can choose to register voluntarily.

If you are not registered for GST, you cannot charge GST and must not include it on your invoices.

What Must Be on an Australian GST Invoice?

The ATO has specific requirements for what a tax invoice must include. Missing any of these can make your invoice invalid.

For sales under $1,000, your tax invoice must include: the words "Tax Invoice" clearly visible (usually at the top), your business name, your Australian Business Number (ABN), the date the invoice was issued, a description of the goods or services sold, the GST amount (either shown separately or a statement that the total price includes GST), and the total price including GST.

For sales of $1,000 or more, you must also include the buyer's name or business name, the buyer's address or ABN, and the quantity of goods or services provided.

How to Calculate GST Correctly

GST is 10% of the price before GST is added. This trips up many business owners.

To add GST to a price, multiply the price by 1.1. Example: $500 × 1.1 = $550 (GST-inclusive price). The GST component is $50.

To find the GST in a price that already includes GST, divide the total by 11. Example: $550 ÷ 11 = $50 (this is the GST amount). The price before GST was $500.

On your invoice, you should show three figures clearly: Subtotal (before GST) $500.00, GST (10%) $50.00, and Total (including GST) $550.00.

This format makes it easy for your client to see exactly how much GST they are paying, which they need to claim GST credits from the ATO.

Step by Step: How to Write a GST Invoice

Follow these steps every time you create an invoice.

Step 1 — Write "Tax Invoice" at the top. The words "Tax Invoice" must appear clearly on the document. Do not just write "Invoice" — it must say "Tax Invoice" to be valid for GST purposes.

Step 2 — Add your business details. Include your full business name exactly as it is registered, your ABN, and your business address. If you operate as a sole trader, use your own name or your registered business name.

Step 3 — Add the invoice details. Include a unique invoice number (e.g. INV-0001), the date the invoice is issued, and if applicable, the due date for payment.

Step 4 — Add your client's details. For invoices over $1,000, include the client's full name or business name and their address or ABN.

Step 5 — List the goods or services. Describe clearly what you sold. Include the quantity, the unit price, and the total amount for each line item. Be specific enough that the client knows exactly what they are paying for.

Step 6 — Calculate and show the GST. Show the subtotal before GST, the GST amount (10%), and the final total including GST as three separate lines. Never just write the total and assume the client can work out the GST themselves.

Step 7 — Add payment details. Include how you want to be paid. Most Australian businesses include their BSB number and account number for bank transfer. You can also include payment terms such as "Payment due within 14 days."

Common GST Invoice Mistakes to Avoid

Not including your ABN. This is the most common mistake. Without your ABN, your invoice is not a valid tax invoice and your client cannot claim GST credits.

Writing "Invoice" instead of "Tax Invoice." The exact words matter to the ATO.

Not separating the GST amount. Your client needs to see the GST component clearly. Do not just write the total.

Using the wrong ABN. Double-check your ABN is correct. You can verify any ABN at abn.business.gov.au.

Forgetting the invoice date. The date matters for your client's record keeping and for your own tax records.

Do I Need Invoicing Software?

You do not need expensive software to create a proper GST invoice. Many Australian sole traders and small business owners use a simple online tool to generate professional PDF invoices without paying a monthly subscription.

A good free GST invoice generator will automatically calculate the 10% GST, include all required ATO fields including your ABN, and let you download a professional PDF ready to send to your client.

Summary

Writing a correct GST invoice in Australia comes down to including the right information in the right format. The ATO requirements are straightforward: your ABN, the words "Tax Invoice", a clear GST breakdown, and the total including GST.

Get these details right every time and you will have no problems with the ATO, and your clients will be able to claim their GST credits without any issues.

This article is for general information purposes only. For advice specific to your business situation, consult a registered tax agent or accountant.