General anti-avoidance rule: arrangements lacking commercial substance may be recharacterised to deny tax benefits and alter tax treatment. A General Anti-Avoidance Rule permits declaring an arrangement an impermissible avoidance arrangement when its main purpose is to obtain a tax benefit; such arrangements may be rebuttably presumed and, if so declared, may be addressed by disregarding, combining or recharacterising steps, treating parties as one, reallocating tax items, recharacterising equity or receipts, and looking through structures to reflect economic substance.