Former UBS banker to America's wealthiest admitted in court to helping U.S. clients hide $20 billion in assets in order to evade paying taxes on those assets.

Bradley Birkenfeld, as part of a plea agreement with the US government outlined the many schemes that he and other former UBS colleagues used to help wealthy Americans hide their money, jewelry and artwork from the IRS. Bloomberg news reports that they used Swiss safety deposit boxes, offshore accounts and accounts set-up under other names to earn about $200 million a year in revenue for UBS.

The Zurich-based firm signed a 2001 agreement with the US government to identify US account holders and their assets held. Birkenfeld helped an American Billionaire in California evade $7.2 million in income taxes by hiding $200 million in assets under Bahamas-based corporations, Liechtenstein trusts and Danish corporations. The billionaire was eventually caught and plead guilty and agreed to pay $52 million in back taxes, interest and penalties.

Birkenfeld faces up to five years in prison and is currently free on a $2 million bond.