If a taxpayer dissatisfied with an assessment or other taxation decision from Australian Taxation Office, the taxpayer may challenge that decision by lodging an objection. The general statutory time limits allowed for the taxpayer to object are 2 years or 4 years depending on the entities.

Generally, individuals and Small Business Enterprises (SBEs) have two years after being issued with a notice of assessment. For all other taxpayers, four years is the relevant period.

If the objection is disallowed, the taxpayer may seek a review by the Administrative Appeals Tribunal (AAT) or appeal to the Federal Court.