The Tax Office has given a grace period to all those stashing their money in offshore havens, saying a crackdown is coming.

The Australian Taxation Office (ATO) has announced the launch of project Do It, a scheme designed to be the last chance for those who may not have declared overseas assets or income to do so before the end of the calendar year.

The ATO says people should come forward now to avoid criminal charges.

Tax Commissioner Chris Jordan says global financial loopholes are being closed.

“Now, as governments around the world step up their data sharing and harness powerful technology to find tax cheats, the concept of the tax haven is actually dying,” Mr Jordan has told the ABC.

“It's just a matter of time before you'll be caught.”

He says people should take advantage of the brief amnesty, during which “they will not be investigated or referred for criminal investigation by the ATO on the basis of their disclosures.”

“The message is now is the time for individuals with offshore income to get their affairs in order and avoid steep penalties and the risk of criminal prosecution,” Mr Jordan said.

Monash University senior taxation law lecturer Ken Devos has told interviewers that incoming techniques for catching people who do not take advantage of the amnesty will be very thorough.

“Particularly the multilateral audits, which have been instigated and all the tax information sharing which goes on now amongst governments and revenue agencies around the world,” he said.