A Gambler’s $600,000 Tax Lesson

Most Australians assume gambling winnings are tax-free, and for the everyday punter having a flutter that is usually right a casual win at the casino or on the punt is not assessable income. But a recent decision of the Administrative Review Tribunal shows how quickly that comfortable assumption can unravel, and how the burden of proof can land squarely on your shoulders.

The case involved a former grocery store worker whose tax return for the 2017 year declared income of just $42,018 in wages. The Tax Office formed the view that she had actually received assessable income of $587,394, more than thirteen times her declared salary and amended her assessment accordingly, with a penalty on top.

How the Commissioner Got to That Figure

Records obtained from The Star in Sydney and on the Gold Coast, and from Crown in Melbourne, showed that roughly $480,000 had been put through casino credit accounts in her name. She said the money came from social gambling, winnings, and loans from friends. The Commissioner’s position was blunt: a person on a modest grocery-store wage simply could not have funded that level of casino activity from her declared income. The unexplained money, in his view, had to be undeclared income.

Here is the part every client needs to understand. Once the Tax Office asserts that you have received income, the law does not require the Commissioner to prove it. When you challenge an assessment, the onus of proof sits with you.

The Burden Falls on You

Under the tax legislation, a taxpayer disputing an assessment must prove that the assessment is excessive  and in practice that means proving where the money actually came from. It is not enough to say these were gambling winnings or a friend lent it to me. You need records, evidence, and a paper trail that stands up to scrutiny.

This taxpayer could not discharge that burden. Her recollection of individual wins and losses ranging from a few thousand dollars up to $137,000 was not backed by the documentation the Tribunal needed.

Because she could not prove the deposits were not income, the Commissioner’s assessment stood.

And Then the Penalty

On top of the tax, she was hit with a penalty. The Tax Office originally imposed a 75% penalty for intentional disregard of the law, later reduced to 50% for recklessness. On a shortfall of this size, that penalty alone runs to a very significant sum, before interest is even added.

The lesson is uncomfortable but important. In a dispute with the Tax Office, you are effectively guilty until proven innocent. If large sums move through your accounts from gambling, gifts, loans, the sale of an asset, or a cash business and you cannot document their source, you are exposed. Bank deposits that do not match your declared income are precisely what the ATO’s data-matching is built to find.

If you have had an unusually large windfall this year, or money moving through your accounts that your tax return does not obviously explain, come and talk to us before the ATO comes calling. It is far cheaper to build the evidence now than to reconstruct it under audit.

t: +61 7 3177 4120
e: advisors@hksrussell.com

Posted on August 12, 2026 by Charisse Russell - Articles