The Australian Taxation Office’s  submission
to the US Senate Committee on Homeland Security and Governmental
Affairs for a hearing into tax haven banks and US tax compliance contains the following points:

• OECD estimates that between $US 5-7 trillion are held in tax havens or banking secrecy jurisdictions.
• the Australian Transaction Reports and Analysis Centre (AUSTRAC) says that in the fiscal year
  ending 30 June 2007, about $16 billion was sent directly to tax havens
  from Australia, and approximately $18 billion was sent directly from
  tax havens to Australia.
• a significant part of the flow of funds to and from tax havens is
  not abusive. These amounts may relate to tourism or travel, or
  legitimate business in goods or services. Another aspect of these funds
  relates to havens as “hubs” for certain financial transactions like
  insurance, private equity or hedge funding. These financial
  transactions may not give rise to tax risk other than in terms of tax
  competition.
• A range of structures or typologies have been identified as
  abusive tax haven schemes. These range from the use of false invoices
  to inflate deductions to the establishment of legal entities to hold
  securities or other assets. The common element in all of these
  typologies is the secrecy or lack of transparency by which beneficial
  ownership can be hidden.
• The ATO’s top priority is to deal very firmly with the worst abuses and
  in particular promoters and their onshore associates who encourage use
  of abusive tax haven schemes. For this purpose, promoters are those who
  design, market or implement abusive haven schemes, and include some
  banks and financiers, accountants and lawyers, agents, trustees and
  brokers. Often based in tax havens or banking secrecy jurisdictions,
  promoters specialise in hiding assets or income so as to divide legal
  and beneficial ownership.