Time is running out fast for investors with offshore bank accounts who may have paid less tax than they should.
They have until 22 June to take advantage of a one-off minimum-penalty offer from the taxman - or face severe financial consequences.
HM Revenue & Customs (HMRC) says penalties will not exceed 10 per cent of any unpaid tax - much less than the level normally charged - if people 'come clean'.
However, the minimum penalty offer has not been widely publicised and Alan McCann, a tax director at UK Top 30 accountancy and advisory firm DTE, fears many people could be unaware of the risks they are running.
"We sent more than 2,000 letters to other firms of accountants, warning that the clock is running down for any clients exposed to this HMRC campaign, and have received feedback from less than one per cent," said McCann.
"I believe more than 100,000 offshore investors nationally may be vulnerable to potential prosecution and financial penalties and it is crucial to act now. The only requirement is that you tell HMRC by 22 June that you intend to make a disclosure. You will be allowed extra time to do actually make the disclosure, but I strongly advise taking professional advice beforehand."
The clampdown follows a Special Commissioners' ruling last year requiring Barclays Bank to provide HMRC with detailed information about offshore account holders.
Barclays co-operated and it is understood four other large banks have been requested to provide similar information.
"The disclosure must include details of the interest paid on funds held offshore, as well as information on where the funds came from in the first place. Where an incomplete disclosure is made the taxpayer may be open to prosecution," added McCann.
"Disclosures must covers all types of UK taxes, potentially going back 20 years. Full interest will be charged on unpaid tax. Anyone with any concerns about the case should contact a professional adviser."
