I hate tax but ATO ID 2002/644 Income Tax Assessability of Prize might be of interest. The ATO states the tests a
Generally, a gift or prize is regarded as a personal windfall gain and not as ordinary income unless the taxpayer has received the prize or gift because of, in respect of, or in relation to any income-producing activity of the taxpayer.
In determining whether a prize or gift is ordinary income, the courts have established that consideration of the whole of the circumstances is necessary and that the following factors need to be taken into account :
• how, in what capacity, and for what reason the recipient received the prize or gift ( Squatting Investment Co Ltd v. Federal Commissioner of Taxation (1953) 86 CLR 570, (1953) 5 AITR 496; (1953) 10 ATD 126 ( Squatting Investment Case ))
• whether the prize or gift is of a kind which is a common incident of the recipient's calling or occupation ( Scott v. Federal Commissioner of Taxation (1966) 117 CLR 514; (1966) 10 AITR 367; (1966) 14 ATD 286 ( Scott's Case ))
• whether the prize or gift is made voluntarily
• whether the prize or gift is solicited ( Hayes v. Federal Commissioner of Taxation (1956) 96 CLR 47; (1956) 6 AITR 248; (1956) 11 ATD 68 ( Hayes' Case ) and Scott's Case )
• whether the prize or gift can be traced to gratitude engendered by some service rendered by the recipient to the prize of gift donor ( Squatting Investment Case )
• the motive of the prize or gift donor (though this factor is rarely decisive in itself) ( Hayes' Case ); and
• whether the recipient relies on the prize or gift for regular maintenance of themselves and any dependants ( Federal Commissioner of Taxation v. Dixon (1952) 86 CLR 540; (1952) 5 AITR 443; (1952) 10 ATD 82 ( Dixon's Case ) and FC of T v. Blake (1984) 75 FLR 315; (1984) 15 ATR 1006; 84 ATC 4661).
I will leave up to far smarter people than I to confirm what all that means.