How to Add GST to an Invoice in Australia

Quick answer

If you’re registered for GST in Australia, you add 10% GST to the taxable amount of each line item. The GST must be shown clearly on a tax invoice — either as a separate line or noted as included in the total. The invoice must say “Tax Invoice”, include your ABN, and show your business name. If you’re not GST-registered, you must not charge GST and must not use the “Tax Invoice” wording — see our guide for that case.

Note: this is general information, not tax advice. Refer to ato.gov.au for authoritative guidance.

Step 1: Confirm you should be adding GST

You add GST if any of these are true:

• Your GST turnover is $75,000 or more in any 12-month period
• You’ve voluntarily registered for GST (even if under the threshold)
• You drive taxis/ride-share — GST registration is required from dollar one

If none of these apply and you’re not registered, stop — don’t add GST. It’s illegal to charge it without registration.

Step 2: Pick GST-inclusive or GST-exclusive pricing

This is the single most common source of confusion. There are two ways to quote a price:

• GST-exclusive (most B2B): “$1,000 + GST”. The client pays $1,100 total. GST appears as a separate line on the invoice.
• GST-inclusive (most B2C): “$1,100 including GST”. The price the client sees already contains the GST.

For consumers, Australian Consumer Law generally requires advertised prices to be GST-inclusive. For business clients, GST-exclusive is the convention — just say so in your quote (“Prices exclude GST”) to avoid disputes.

Step 3: Do the maths

GST in Australia is a flat 10%. The simplest formulas:

• From GST-exclusive to inclusive: exclusive × 1.10
• GST amount from exclusive: exclusive × 0.10
• GST amount from inclusive: inclusive ÷ 11
• From GST-inclusive to exclusive: inclusive ÷ 1.10

Two worked examples:

Example 1 — GST-exclusive quoting. You quote a copywriting job at $2,000 + GST. The line item shows $2,000. GST = $2,000 × 0.10 = $200. Invoice total = $2,200. The client pays $2,200.

Example 2 — GST-inclusive quoting. You sell a finished product for $99 including GST. The GST portion = $99 ÷ 11 = $9. The GST-exclusive amount = $90. On the invoice you show: subtotal $90, GST $9, total $99 — or note “Total includes $9 GST”.

Step 4: Show GST correctly on the invoice

A compliant Australian tax invoice with GST must include:

1. The words “Tax Invoice” clearly visible
2. Your business name (or trading name)
3. Your ABN
4. The issue date
5. A description of what was supplied
6. The GST amount — shown as a separate line or stated as included
7. The total price in AUD

For full details on every required field, see what must be on a tax invoice. For invoices over $1,000, the buyer’s identity (name, business name, or ABN) is also required — see tax invoices over $1,000.

Mixed invoices: some GST, some GST-free

Some supplies are GST-free in Australia — most fresh food, certain medical and education services, exports, and a few other categories. If your invoice mixes taxable and GST-free items, structure it like this:

Web design — hours              $1,500.00       (GST)
Stock photography licence       $   200.00       (GST-free)

Subtotal (taxable):             $1,500.00
Subtotal (GST-free):            $   200.00
GST:                            $   150.00
Total (AUD):                    $1,850.00

Clarity is the goal — a bookkeeper or the ATO should be able to see at a glance which amounts attracted GST and which didn’t. Free Invoice App lets you toggle GST on or off per line item and handles the totals automatically.

Rounding rules

The ATO allows two rounding methods:

• Total invoice rule: calculate GST on the GST-exclusive total of the invoice, then round to two decimal places at the end. This is what most accounting software uses.
• Taxable supply rule: calculate GST on each line item and round each one individually before summing. Used in some industries with line-level reporting.

For most freelancers and sole traders, the total invoice rule is correct and the default in Free Invoice App. Use the same method consistently across all your invoices.

What to write if you’re NOT registered for GST

If you’re under the $75,000 threshold and not registered:

• Do not use the words “Tax Invoice” — just “Invoice”
• Do not include any GST line
• State on the invoice: “No GST has been charged”
• If a client asks “Where’s the GST?”, point them to the ATO’s $75k registration threshold

Full walkthrough in how to invoice if you’re not registered for GST.

How Free Invoice App handles GST

Free Invoice App keeps your GST status in one place. When GST-registered is on, every invoice automatically shows the “Tax Invoice” header, calculates 10% on taxable lines, and shows the GST line in the totals. Per-line GST toggles handle mixed invoices. If you cross the $75k threshold mid-year, flip the switch once and every new invoice from that day picks up the change. Get started free — the Starter plan handles GST and non-GST invoices.

Frequently asked questions

What’s the easiest way to calculate 10% GST?

GST-exclusive amount × 0.10 = GST. GST-inclusive total ÷ 11 = GST. Free Invoice App does this automatically when you toggle GST on.

Do I have to show GST separately on the invoice?

For invoices over $1,000, yes. Under $1,000, you can show it separately or note that the total includes GST. Showing it separately is always clearer.

Can I charge GST if I’m not registered?

No. Charging GST without being registered is illegal in Australia. You also must not use the words “Tax Invoice”.

How do I show GST on a mixed invoice?

List each line and mark its GST status. Show subtotals for taxable and GST-free amounts, then the GST total, then the grand total.

Should I quote GST-inclusive or GST-exclusive?

GST-inclusive for consumers (consumer law). GST-exclusive is conventional B2B — just state it clearly in the quote.