HM Revenue & Customs (HMRC) is to hire an additional 100 inspectors dedicated to making sure wealthy people pay enough tax.
The Affluent Compliance Team currently has 200 staff but is recruiting as its work expands.
HMRC said in addition to taxpayers with an annual income of more than £150,000 and wealth of between £2.5m and £20m, the unit will also cover those with wealth in the range £1m to £2.5m.
By the end of December the unit had brought in an extra £75m in tax - well ahead of expectations - with a target of £586m by the end of 2015.
Exchequer secretary David Gauke said: "HMRC set up the new affluent teams from some of the £917m we made available in 2010. The team has made a great start by bringing in £75m in additional tax that would otherwise have been lost to the country.
"The vast majority of people pay their way. Dodging tax is immoral, illegal and unaffordable and the minority who cheat are increasingly finding that, thanks to the work of the Affluent Team, they have made a big mistake."
Affluent Compliance Team director Roger Atkinson said: "In September 2012 the government announced an additional investment of £5m, enabling us to recruit an extra 100 inspectors. We will recruit from within HMRC and externally and the new team will be fully operational by April and focused on delivering an additional £75m a year.
"Good quality intelligence is central to catching the cheats and so we are expanding our affluent intelligence unit fourfold. This is very good news for all honest taxpayers."
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