The difference between the Liechtenstein amnesty and New Disclosure Opportunity (NDO) for offshore savers is "unfair", according to PKF Accountants.
The UK Government is expected to announce a deal today with Liechtenstein, the tiny Alpine principality, to effectively end secrecy for Britons who hold accounts in the tax haven.
Liechtenstein, Monaco and Andorra have been cut from the Organisation for Economic Co-operation and Development's (OECD) "un-cooperative" list, as other jurisdictions enter a flurry of tax agreement signing in a bid to improve their transparency.
Thousands of British investors with up to £3bn stashed in secret Liechtenstein bank accounts will be asked to come forward voluntarily under a deal to be negotiated next week that could be the first of many worldwide.