A parliamentary hearing heard last week how HMRC has collected £135m from clients on a leaked list of HSBC's private banking operation in Switzerland.
The Revenue appeared before the Public Accounts Committee (PAC) last Wednesday to discuss their Standard Report 2013/14.
Chief executive Lin Homer said that one person on the list of 24,000 had been prosecuted, paying fines of more than £830,000 in 2012, but that 13 investigations were ongoing.
"So far we have a yield of £135m, but we're not finished," Homer said, adding that there were specialists working on the cases within enforcement compliance.
The list was leaked by former employee Herve Falciani in 2010. On it were 6,800 entities with British addresses. Some of the data wasn't good enough quality for HMRC to pursue, however they did identify 3,600 taxpayers, the affairs of whom they did look into.
HMRC figures at the hearing showed that other countries had retrieved more, with Spain taking in £220m and France £188m.
But the Revenue added it would rather they came to them voluntarily rather than carry out criminal prosecutions, due to the time it would take to get through 3,800, Homer told the PAC.