Constitutional changes at the time of Federation in Australia required the harmonisation of the excise tax rates of the former Colonies. This paper outlines the excise tax systems of the Colonies before Federation and that of the Commonwealth after Federation. Estimates are made of the consumer tax equivalent rates and of the implicit rates of protection in each Colony and in the Commonwealth after Federation. The Commonwealth Government harmonised the excise tax rates of the Colonies at about the mid‐points of the rates of the Colonies but the implicit rates of protection increased after Federation.