The Australian Taxation Office is on the hunt for 5600 Australian taxpayers who didn't respond to letters about hiding cash and assets in tax havens as part of the Offshore Voluntary Disclosure Initiative.

The ATO says it is well placed to track them down, last week unveiling a new weapon in its fight against tax haven cheats known as the Multilateral Convention. Australia and 42 other countries from across Europe, South America and Africa have agreed to share information and conduct joint audits.