The UK government has agreed measures with Switzerland to tackle offshore tax evasion. Under the terms of an agreement, existing funds held by UK taxpayers in Switzerland will be subject to a significant one-off deduction of between 19% and 34% to settle past tax liabilities.
From 2013, a new withholding tax of 48% on investment income and 27% on gains will ensure the effective future taxation of UK residents with funds in Swiss bank accounts. This will be accompanied by new information-sharing rules which will make it easier for HMRC to find out about Swiss accounts held by UK taxpayers. The new charges will not apply if the taxpayer authorises a full disclosure of their affairs to HMRC.
More information can be found at HMRC here.