Commissioner for Taxation Michael D’Ascenzio has signed a letter to 1,200 people with a personal wealth of more than A$30 million, advising them to keep their financial affairs above board.

“We acknowledge the contribution which most wealthy people make to our economy and tax revenue,” says Mr D’Ascenzio, before going on to warn that “over the next few years we will almost more than triple the number of officers dedicated to monitoring wealthy people”.

“I suggest you review your tax affairs in consultation with your advisor and consider how the tax office is likely to view your approach,” he said.

The letter is the latest in a strong campaign against tax avoidance by Australia’s wealthy from the Australian Taxation Office, and is a companion to a dowloadable booklet called Wealthy and Wise – available on the ATO website.

Australians with wealth of A$30 million or more also automatically field a targeted 54-page ATO questionnaire which effectively audits them even before they lodge their tax returns.

The ATO spent A$300 million with the Australian Crime Commission on "Operation Wickenby” to prove the offshore tax affairs of high profile wealthy Australians, such as actor and director Paul Hogan.

Through the US Internal Revenue Service, the ATO has launched legal proceedings in the US to gain access to Mr Hogan’s bank records going back nine years. Australian media reports have claimed that Mr Hogan used a complex system of offshore trusts to hide A$40 million from the ATO.

Music entrepreneur Glenn Wheatley was recently released after serving a jail term for not paying tax on almost A$320,000 of income, while two other Wickenby suspects, John and Judith Barnes, have fled from Australia owing A$10 million in back taxes.

Australia’s second richest man, shopping mall magnate Frank Lowy, has also been named, with reports that he used an offshore foundation in Liechtenstein to hide up to $100 million in assets. Mr Lowy has strenuously denied the allegations.

The investigations have even reached into the upper echelons of the ATO itself, with one-time ATO star tax lawyer Nick Petroulias recently jailed for two years after being convicted of giving favourable tax rulings to companies in which he had a financial interest.

The ATO says that it has collected more than A$70 million from people investigated by Wickenby, and has raised A$157 million in liabilities.