"We've finalised a little under half, about 250.

"We've got another 125 in progress and the remaining 200 we will have completed by June 30 next year."

Mr Olesen said about $50 million worth of tax liabilities had been raised as a result of the Panama Papers probe.

Project DO IT (disclose offshore income today) was a tax amnesty for returning offshore cash and assets. Thousands of taxpayers reported $240 million in additional income and $1.7 billion in offshore assets.

The International Consortium of Investigative Journalists used the Panama Papers to reveal how politicians and the wealthy used shell companies to shield illicit gains and dodge taxes.

Will Day, the ATO's deputy commissioner of private groups and high wealth individuals, said there were a small number of cases being investigated in Australia on a "criminal basis".

"Search warrants have been executed by both the Australian Federal Police and the Australian Criminal Intelligence Commission and they relate to ongoing criminal investigations into a number of individuals who've been linked to the Panama Papers," he said.

Mr Day has taken over from Michael Cranston, who resigned in June after being charged with seeking to use his position to help his son, Adam.


Tax Commissioner Chris Jordan used the Senate Estimates hearing to provide an update on several simultaneous investigations occurring into the Cranston matter.

"The APS [Australian Public Service] code of conduct investigations into ATO staff have been finalised, and we confirm breaches of the code were found," he said.

"I cannot however go into the nature or details of the breaches.

"Of the three SES officers investigated, two have returned to the ATO with sanctions, and the third, Michael Cranston, resigned in June."

Operation Elbrus was the name given to the joint investigation of tax fraud syndicate that allegedly fleeced more than $100 million from the ATO. Police claim Adam Cranston was one of the ringleaders.

"Following the Elbrus revelations, I commissioned a range of reviews into our fraud control work, frameworks, policies and procedures," Mr Jordan told Estimates.

"In addition, a number of other reviews were instigated including the one that this Committee requested of the Inspector General of Taxation.

"These multiple reviews and investigations, both internally and using external parties, are all at different stages of completion and I am pleased to say that to date there have not been any significant systemic issues found.

"We've found a few suggestions for improvements, as you would expect when so many people are looking at these processes across multiple reviews."

In April, 2016, the ATO revealed it was investigating more than 800 high net wealth Australian clients of Mossack Fonseca.