Hundreds of secret bank accounts have been uncovered in two Swiss banks after whistle blowers handed sensitive information about customers to the UK tax man.
An HM Revenue & Customs task force is poring through the information before contacting taxpayers and sharing their confidential banking data with other countries.
One of the banks is foreign-owned and has thousands of customers across 100 countries, HMRC disclosed.
The ink has hardly dried on a tax agreement between the UK and Switzerland that is expected to generate billions of pounds of lost tax on investment earnings held in Swiss banks.
The agreement followed other disgruntled bank employees handing over lists of customers and accounts to tax authorities in the UK, France, Germany and the US.
The revelations led to some tough talking between the Swiss and UK government and underlies much of the new anti-tax avoidance legislation introduced in the US, UK and Europe.
HMRC refuses to talk about the Swiss banking task force.
“We don’t comment on information we receive but we get information from a wide variety of sources which we carefully examine to make sure everyone pays the right tax,” an HMRC spokesman. “Tackling tax evasion is a top priority and the days of hiding money offshore to evade UK tax have gone.”
From next year, hiding money offshore will become more difficult for tax cheats.
The US Foreign Account Tax Compliance Act (FATCA) will require Swiss and other non-US financial institutions to deliver an annual report on holdings in accounts controlled by US taxpayers.
US taxpayers will also have to declare any investments overseas when filing their annual tax return on pain of fines of up to $50,000.
The UK is also considering a general anti-avoidance rule (GAAR) aimed at tightening up loopholes that let taxpayers evade tax.