How GST Works in Australia: A Plain-English Guide

The Goods and Services Tax sits in almost every price you pay. Here is how the 10% works, and how to add it or strip it out.

Plantrino Guides · Updated 2026 · About a 9-minute read

GST is one of those taxes that is everywhere and yet rarely explained. It is built into most prices so quietly that many people never think about it — until they need to invoice a customer, claim it back, or simply work out how much of a bill is tax. This guide explains Australia's GST in plain terms.

What GST Is

GST stands for Goods and Services Tax. It is a broad-based tax of 10% applied to most goods and services sold or consumed in Australia. It has been set at 10% since it was introduced in 2000.

GST is a consumption tax — it is ultimately paid by the end consumer. Businesses act as collectors: they add GST to their sales, and pass it on to the Australian Taxation Office, while being able to claim back the GST they paid on their own purchases.

Adding GST to a Price

If you have a price before GST and want the GST-inclusive total, you add 10%:

A service priced at 200 before GST becomes 200 × 1.1 = 220 including GST. The GST portion is 20.

Removing GST from a Price

This is the part that trips people up. If a price already includes GST and you want to find the GST amount, you do not simply take 10% off — because the 10% was added to the smaller pre-GST figure, not the total.

Instead, the GST inside a GST-inclusive price is found by dividing by 11:

For a 220 inclusive price: 220 ÷ 11 = 20 of GST, leaving 200 before GST. The "divide by 11" rule is the single most useful thing to remember about GST. Taking a flat 10% off the total would wrongly give 22.

Where You Actually Meet GST

For most people, GST shows up in three everyday places. First, on receipts: many dockets show a GST line near the bottom, which is simply the total divided by 11. Second, in advertised prices: prices shown to ordinary consumers in Australia are generally displayed with GST already included, so the number on the shelf is the number you pay. Third, in quotes and invoices between businesses, where prices are often quoted before GST — which is exactly where the confusion starts.

That last one deserves a warning. If a tradesperson quotes you "1,500 plus GST", the bill will arrive at 1,650. Neither of you did anything wrong — you were just using different conventions. Whenever a quote matters, confirm one thing up front: is that figure including or excluding GST? One short question prevents most GST arguments.

A Worked Example: One Job, Both Directions

Say a cleaner who is registered for GST quotes 1,500 excluding GST for a job.

Adding GST for the invoice: 1,500 × 1.1 = 1,650. The invoice shows 1,650 including 150 of GST.

Now reverse it. The customer sees only the 1,650 total and wants to know the tax inside it: 1,650 ÷ 11 = 150. Same number, reached from the other side. Notice what does not work: 10% of 1,650 is 165, which is wrong by 15. On bigger amounts, that error grows — on a 66,000 renovation the wrong method would overstate the GST by 600.

The cleaner's side continues after the invoice. Suppose they also bought 440 of cleaning supplies (including 40 GST) for the job. They collected 150 of GST from the customer and paid 40 of GST to their supplier, so at reporting time they pass on the difference: 150 − 40 = 110 to the ATO. That claiming-back mechanism is called an input tax credit, and it is why GST is designed to tax the final consumer rather than every business along the chain.

What Is GST-Free

Not everything carries GST. Australia keeps certain essentials GST-free, meaning no 10% is added. Common GST-free categories include most basic foods, many health and medical services, and certain education and childcare. The detail can be intricate — plain bread may be GST-free while a similar prepared item is taxed — so the rules reward checking rather than assuming.

There is also a separate category the tax law calls input-taxed, which covers things like many financial services and residential rent. From a consumer's point of view the effect looks similar — no GST line on the bill — but the mechanics behind the scenes differ. The practical takeaway is simple: not every price divides by 11, so do not assume every bill contains GST.

Who Needs to Register for GST

Not every business charges GST. Registration is generally required once a business reaches a turnover threshold, and is optional below it. A business registered for GST must add GST to its taxable sales, issue tax invoices, and report through Business Activity Statements. Because thresholds and rules can change, anyone running a business should confirm current requirements with the ATO or an accountant.

One consequence surprises new customers of very small operators: an unregistered business does not charge GST at all. If a hobby-scale gardener bills you 300, there is no GST inside that figure to claim or remove. And on the other side, a registered business that forgets to add GST to a quote still owes the ATO its share — the 10% comes out of their own margin instead.

Common GST Mistakes

Subtracting 10% instead of dividing by 11. The classic. It always overstates the GST, and the gap grows with the amount involved.

Comparing quotes that use different conventions. A 1,600 including-GST quote is cheaper than a 1,500 plus-GST quote. Convert both to the same basis before deciding.

Treating collected GST as income. For business owners, the GST portion of every sale is money held for the ATO, not profit. Businesses that spend it during the quarter meet an unpleasant surprise at BAS time. A separate set-aside account is the time-honoured fix.

Assuming every expense includes GST. GST-free and input-taxed purchases contain no GST to claim back. Claiming a credit on them is an error the ATO can unwind later.

Frequently Asked Questions

GST is a flat 10% woven through most Australian prices. Adding it means multiplying by 1.1; finding the GST already inside a price means dividing by 11. Master those two moves, and the rest — what is GST-free, who must register — is just detail you can look up when you need it.