Substance over form: economic reality can override legal form to recharacterise transactions and curb tax avoidance schemes. Judicial anti-avoidance doctrines focus on the Business Purpose Rule, requiring commercial justification beyond tax savings, and the Substance over Form rule, which gives economic reality precedence over legal form. The substance doctrine covers legal versus economic substance, sham transactions, wrong characterisation, step-transaction treatment, and piercing the corporate veil to disregard formal structures used to alter tax outcomes.