Bottom of the harbour tax avoidance was a form of tax avoidance used in Australia in the 1970s. Legislation made it a criminal offence in 1980. The practice came to symbolise the worst of variously contrived tax strategies from those times.
In its 1986/87 annual report, the Australian Taxation Office (ATO) stated a total 6,688 companies had been involved, involving revenue of between $500 million and $1 billion.