HM Revenue & Customs (HMRC) has brought in £500m in extra tax, after the creation of a crack unit focused on the country's wealthiest people three years ago.
The High Net Worth Unit (HNWU) - which deals with the UK's 5,000 richest taxpayers who have assets of more than £20m - said it had exceeded its collection targets.
Unit head Martin Randall said: "The tax affairs of the richest people in the country are, by their nature, complex, and that's why we have focused resources on getting their tax right.
"The majority of the wealthiest taxpayers play by the rules, paying the right tax at the right time, but we take action against the minority who don't."
Initial projections thought the unit would bring in about £100m a year, but in 2011-2012 its tax yield reached £200m. This was up from £162m in 2010-2011 and £83m in 2009-2010. So far this year it has brought in £55m.
Exchequer secretary David Gauke said: "Today's figures show that HMRC's High Net Worth Unit is making sure that the country's wealthiest citizens pay the tax they owe. The government is committed to a fair tax system where those with the most contribute the most.
"The overwhelming majority of people pay their taxes, so it is absolutely right that HMRC pursues anyone who tries to avoid their responsibility."
The unit is staffed by 380 people.
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From 1 March