Criminal charges are being brought against the seven defendants in a Singapore court after they are accused of taking clients' details with them when they defected to work at rival bank UBS in 2006.
Originally Citibank filed a lawsuit against some of the group, claiming that they had taken the data of wealthy clients - investing nearly $7 million each with the bank - over to UBS with them.
Although the bank's civil case had been settled after three of the bankers were accused of stealing $35 million worth of business, Singapore police now want to prosecute.
As well as facing 20 years in jail, the seven could be fined over $70,000 if found guilty of the 1,223 charges against them under the Computer Misuse Act, Reuters reports.
Two of the group were not those named in the Citibank civil suit, but all have been granted bail before the case comes to trial.