Cusack v Commissioner of Taxation

Cusack v Commissioner of Taxation concerned a challenge to the validity of tax assessments due to the presence of two types of Australian dollars with different exchange values. The applicant argued that the existence of these two currencies created uncertainty in the assessments, rendering them void for uncertainty and excessive. Alternatively, the applicant claimed that he had the right to have his income expressed and assessed in high value Australian dollars, which would reduce his assessable income and tax liability by a factor of 5:1, making the assessments excessive by that factor and thus void. The central legal issue before the court was whether the presence of two types of Australian dollars with differing exchange values necessitated a reassessment of the applicant's income and tax liability, and whether the assessments were void for uncertainty or excessive.

The court considered the Currency Act, which designated the Australian dollar as the sole legal tender and outlined the denominations of money. It also examined the provisions regarding the issuance of coins and their legal tender status. The court found that the Currency Act provided a clear framework for the monetary unit of Australia and established the legal tender status of coins. Despite the existence of two types of Australian dollars, the court held that the assessments were valid as they were made in accordance with the Currency Act, which recognises only one type of Australian dollar. The court concluded that the applicant's arguments were based on a misinterpretation of the Currency Act and did not affect the validity of the tax assessments. The court dismissed the application and ordered the applicant to pay the respondent's costs.