The bank is the latest lender to be caught up in the crackdown by the US Department of Justice as it has ties to four private bankers indicted in February for helping a number of Americans avoid having to pay their taxes.
These men were Marco Parenti Adami, Emanuel Agustoni, Michele Bergantino and Roger Schaere - and they were accused of committing fraud and conspiracy.
It was alleged that the employees helped clients set up offshore accounts using fake names, as well as transferring cash from Credit Suisse accounts to private ones located in Switzerland.
The bank - which was founded in 1856 by the politician and business leader Alfred Escher - said: "Subject to our Swiss legal obligations, we will continue to cooperate with the US authorities in an effort to resolve these matters."
By Claire Archer