Australia  ·  2026

One eleventh of what you were paid was never yours.

Australian invoices are quoted GST-inclusive, so a registered sole trader paid $110,000 did not earn $110,000 and owe GST as well. They earned $100,000 and have been holding $10,000 for the ATO since the day it cleared. Calculators that add 10% on top get both the tax and the money in hand wrong, in opposite directions.

The first year arrives all at once

PAYG instalments only begin after a return has been lodged showing tax of $1,000 or more. A first full year generates no instalments at all and then one lodgment bill for the whole year — often more than a year after the first invoice was paid, by which time the money has usually been spent.

The Medicare levy phases in

It is not 2% above a line and nothing below it. Between $28,011 and $35,013 it is 10% of the excess, which is a very steep effective rate across a narrow band — exactly the band a part-time sole trader is standing in.

The $75,000 GST threshold is a forecast, not a history

Registration is compulsory once turnover reaches $75,000 in any twelve months, and signing a contract that will take you over it triggers it before the money arrives. You then have 21 days. Until you register you cannot charge GST, but the ATO can still assess you for GST on sales made after you crossed the line.

The offset most sole traders never claim

The small business income tax offset is 16% of the tax on your business income, capped at $1,000 a year. It is applied automatically here, which is more than can be said for most rules of thumb.

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Set aside

Show the working

What this does not cover. HELP and student loan repayments, capital allowances and super contributions are not modelled. Nobody pays super for a sole trader, so the figure assumes you contributed none.

Track it all year

The calculator answers today. The app remembers, watches every invoice, and in December tells you what you forgot to claim.

Try it with your own figures

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