GST Calculator Australia

Because the rate is exactly 10%, a GST-inclusive price is 11 elevenths of the base. To find the GST in a tax-inclusive amount, divide by 11: on A$110 the GST is A$10, and the base is A$100. That is exact, not an approximation, and it works on any amount.

The error to avoid is subtracting 10% from the inclusive total. A$110 minus 10% is A$99, not A$100 — a shortfall of A$1 on every hundred dollars. It is a small percentage and a large amount over a year of invoices, and it misstates both your reported income and your GST liability.

Registration for GST is generally required once your annual turnover reaches A$75,000, or A$150,000 for a non-profit organisation. Below that it is optional — and voluntary registration means you charge GST but also claim credits on your business purchases, which can be worth it in a year with significant equipment or setup costs.

There is one category where the threshold does not apply at all: providing ride-sourcing or taxi travel requires GST registration from the first dollar, regardless of turnover. A driver earning A$20,000 must be registered where a consultant earning the same amount need not be.

GST-free supplies are taxed at 0%, and you still claim credits on the costs of making them. Most basic food, most health and education services, and exports fall here. It is the favourable category: no GST charged to the customer, full recovery on your inputs.

Input-taxed supplies carry no GST and give no credit recovery. Residential rent and most financial supplies are the main examples. The distinction is invisible on an invoice — both show no GST — and decisive for what you can claim back. Treating an input-taxed supply as GST-free means claiming credits you are not entitled to.

This calculator applies the 10% rate to an amount. It does not classify your supply into taxable, GST-free or input-taxed, and that classification is what determines whether the 10% belongs on the invoice at all.

To claim a GST credit on a purchase over A$82.50 including GST, you need a valid tax invoice from the supplier. It must be labelled as a tax invoice and show the seller's ABN, the date, a description of what was supplied, and the GST amount or a statement that the total includes GST. A receipt without an ABN will not support a claim.

GST is reported through the Business Activity Statement, most commonly quarterly. What you remit is the GST you collected minus the credits on your purchases — a net figure across the period, not a per-transaction amount. The most common cash flow error in a first year is treating collected GST as revenue and spending it before the BAS falls due.