How it's calculated
Adding GST: GST = price × 10% total = price × 1.1
Removing GST: price = total ÷ 1.1 GST = total ÷ 11
A quick check: the GST in any GST-inclusive price is one-eleventh of that price.
Worked examples
$1,000 excluding GST → GST $100 → $1,100 including GST
$1,100 including GST → GST $100 → $1,000 excluding GST
$550 including GST → GST $50 → $500 excluding GST
When to register for GST
- You must register within 21 days once your GST turnover reaches, or is expected to reach, $75,000.
- Taxi and ride-sourcing drivers must register whatever their turnover.
- Below $75,000 you can choose to register, then you must charge GST and lodge activity statements.
What this calculator doesn't cover
- GST-free sales (such as most basic food, some health and education) and input-taxed sales.
- Exports and services to overseas customers, which are often GST-free.
Frequently asked questions
How do I work out GST from a total?
Divide the GST-inclusive price by 11. For example, a $220 invoice includes $20 of GST.
Do freelancers have to charge GST?
Only once you're registered. If your turnover is under $75,000 and you haven't registered, don't add GST to your invoices.
Source: ATO: registering for GST.