Taxpayers with an offshore account or asset and tax to pay should make a notice of intention of disclosure by 30 November 2009 if they intend using the "New Disclosure Opportunity" to bring their tax affairs in order. On making the notice of intention of disclosure, a full disclosure using the paper forms is due by 31 January 2010 or a full disclosure online is due by 12 March 2010. Full payment of undeclared taxes, interest and penalties is required on submission of the full paper or electronic disclosure.
Full details of HMRC's offshore accounts and assets enquiry is available here