HM Revenue & Customs has managed to recover £3.65bn in owed revenue as it clamps down on UK tax evaders.
HMRC's top investigators managed to claw back the extra money thanks to increased scrutiny of tax avoidance schemes, tax evasion and fraud.
Law firm Pinsent Masons found that HMRC's Special Investigations team had the most successful year to date: lost taxes were up by almost a quarter on 2012/13's recovered income of £2.97bn ($4.7bn, €3.8bn).
The takings constitute a tenth of the predicted £34bn tax gap thought to be affecting the UK.
Paul Noble, tax director at Pinsent Masons, said: "These figures should be a massive jolt to anyone with undisclosed or outstanding tax liabilities that have given them significant savings. HMRC has been recruiting and training heavily in order to increase the activity of its specialist investigations team. That new capacity is now clearly on-stream.
Noble pointed out that UK tax authorities are better equipped to chase down tax dodgers, are taking an uncompromising approach to investigations, and have become "far more hard-nosed when it comes to settling cases".
"This increased investigatory capacity comes with a raft of other headline-hitting new HMRC powers, such as more criminal sanctions for offshore bank account holders and new accelerated payment measures," he added.