GST Calculator

How do I calculate the GST in a price?

To find the GST inside a GST-inclusive price, divide the total by 11. That works because a GST-inclusive price is 11 equal parts: 10 parts base price and 1 part GST. So a $1,100 invoice includes $100 of GST ($1,100 divided by 11). To add GST instead, multiply the GST-exclusive amount by 1.1.

Is GST always 10%?

The GST rate in Australia is 10%, and it has not changed since GST began in 2000. Not everything carries it, though: some items are GST-free, such as most basic food, and some are input-taxed. If you are unsure how GST applies to what you sell, check with the ATO or your accountant.

How the GST calculation works

To add GST, the calculator multiplies your amount by the GST rate and adds it on, so a $1,000 amount at 10% becomes $1,100 including $100 of GST. To remove GST, it works backwards from the GST inclusive figure: it divides by 1 plus the rate to find the base amount, then the GST is the difference. GST registered businesses generally include GST in their prices and report it to the ATO.

Financing a GST-inclusive purchase

Equipment quotes usually show the GST-inclusive price. A machine at $66,000 inc. GST is $60,000 plus $6,000 GST. A GST-registered business can generally claim that $6,000 as an input tax credit on its next BAS, while the finance can be written over the full $66,000. Timing depends on your accounting basis, so check with your accountant: general information, not tax advice. To see indicative repayments on an asset like this, try the asset finance calculator, or read how equipment finance works.

BAS or GST debt you cannot pay this quarter

If the BAS is lodged but the GST owing cannot be paid in full, the two usual routes are an ATO payment plan or paying the debt out with a business loan. Since 1 July 2025, ATO general interest charge (GIC) is no longer tax deductible, which changes that comparison; confirm your own position with your accountant. Our article on ATO payment plans versus paying it out works through a $48,000 example with the 2026 numbers. Lodge on time either way: late lodgment is a separate problem. For the finance side, see business loans.