Tax avoiders will be forced to hand £500m to HM Revenue & Customs (HMRC) after a ruling by the Supreme Court.
Judges decided unanimously that HMRC could force 200 people to pay tax bills while their avoidance scheme was being investigated, the Times reports.
In a test case, a member of a scheme argued that he did not have to pay his tax bill for 2007-08 because he was claiming more in tax relief for 2008-09, but the judges said that HMRC did not have to award any tax relief while it made its inquiries.
HMRC will now be able to claw back £60m in tax from the scheme. Members of similar schemes will be forced to pay a further £440m, HMRC said.
"HMRC is relentless in pursuing taxpayers who participate in avoidance schemes," an HMRC spokesman said.
"We will challenge them, including litigating, if we cannot reach a satisfactory settlement through discussion.
"While we are checking whether their scheme results in relief from tax, we will ensure they don't enjoy an unfair cash flow advantage by not paying any undisputed tax during our inquiry."
Lawyers suggested that HMRC's win lay in a technicality that could be easily sidestepped in the future.
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