The onus or requirement of proof differs in different kinds of disputes in Australia. The most familiar is the burden or onus on a prosecution in a criminal court to establish a case beyond reasonable doubt. In civil court cases the burden or onus is on a claimant to prove a case on the balance of probabilities. In those kinds of cases the defendant may not need to prove anything.

Burden of proof in tax cases

In tax cases a reverse burden or onus applies. A tax assessment is taken to be right unless the taxpayer can prove otherwise.

Why is that? The answer is probably more practical than philosophical. In any case, it’s a bad idea not to return income and to wait for the commissioner to do the task because the commissioner’s findings will be hard to rebut if the commissioner is taken to be right to begin with.

Either in the case of a decision on an income tax objection:

• which is being reviewed by the Administrative Appeals Tribunal; or
• which is appealed to the Federal Court;

the burden of proving that the assessment is excessive or is otherwise incorrect and of proving what the assessment should have been is on the taxpayer under the Taxation Administration Act (C’th) 1953. Similar state laws putting the burden of proof on to taxpayers apply to state taxes.