Australian GST Invoice Calculator

Use this Australian GST invoice calculator to work out the GST amount, GST-inclusive total and GST-exclusive price for a taxable sale. Australia’s standard GST rate is 10%. It does the arithmetic; it does not decide whether your transaction is taxable.

Amount before GST

Australian GST invoice formula

For an amount before GST, GST = amount × 10%. The GST-inclusive total = amount × 1.10. To extract GST from a GST-inclusive total, GST = inclusive total × 10 ÷ 110, which is the same as total ÷ 11.

Worked example: a Newcastle electrician’s invoice

A Newcastle electrician finishes a rewiring job quoted at $2,750 GST-exclusive. The GST is $2,750 × 10%, which is $275, so the invoice total is $3,025. She sends the tax invoice showing all three figures clearly. When the client queries the total, she checks it backwards: $3,025 ÷ 11 is $275, which matches. On her next BAS she reports $2,750 of sales and $275 of GST collected. Try $2,750 in the calculator above and you will see GST of A$275.00 and a total of A$3,025.00. For the reverse calculation, the GST on invoice calculator works from any starting figure.

When to use it

Prepare or check a simple invoice or quote.
Convert an exclusive price to an inclusive price.
Separate GST from an inclusive total.
Check GST arithmetic before recording a transaction.

Practical tips for invoicing like a pro

Quote the basis every time: “$2,750 plus GST” beats a bare “$2,750” that invites arguments. Include all the tax invoice details the ATO requires for the amount, and run the finished invoice through the Australian tax invoice checklist before sending. Send invoices promptly, because late invoices mean late payments and late GST attribution headaches. If you undercharge, fix it with an adjustment note rather than editing the original.

What it does not decide

The calculator cannot classify supplies as taxable, GST-free or input-taxed, and it does not handle complex adjustments. Check the ATO rules for your transaction.

Frequently asked questions

What must my tax invoice show?

Your identity and ABN, the date, a description of what was sold, the amounts and the GST information. Larger invoices need more detail.

When do I have to issue a tax invoice?

For taxable sales, with the detail required depending on the invoice amount. For sales under $82.50, the rules are simpler.

Can I round the GST?

Yes, round to the nearest cent on each line. The total GST is the sum of the rounded lines.

What if I make a mistake on an invoice?

Do not just edit the original. Issue a credit note or adjustment note so both sides have a clear paper trail.

Related tools

Official source

See the Australian Taxation Office for current GST obligations and tax invoice requirements.