This article explains the constitutional basis of taxation in Australia, focusing on sections 51(ii), 90, 53, 55, and 96 of the Australian constitution. It discusses the power division between the commonwealth and the states, the imposition of custom and excise duties, and the conditions for granting financial assistance to states. The article also covers the limitations on the power of the senate to amend tax-related bills and the requirements for legislation dealing with taxation and custom and excise.