Savers who have sidestepped the taxman by stashing their money offshore may be able to use a loophole to cut the amount of tax they pay if they come clean, according to tax lawyers.

Savers who redirect their cash into an account in the tax haven of Liechtenstein before owning up can halve the money they repay to HM Revenue & Customs.

The loophole has arisen because of a discrepancy between two tax amnesties recently introduced by HMRC: the first for savers with offshore accounts opened at bank branches in the UK; and another especially for savers with money in Liechtenstein.

Under the terms of both deals, all savers who come forward will have to repay all unpaid tax and will have the penalty payment capped at 10 per cent of the outstanding tax.

While savers under the UK scheme, called the New Disclosure Opportunity, must repay outstanding tax over the past 20 years, those with cash in the principality of Liechtenstein need only backdate their payments for ten years, saving them thousands if not millions of pounds.

Phil Berwick, director of tax investigations at McGrigors, the law firm, said: “A UK resident who deposited £1 million from undeclared income or gains into an offshore account 20 years ago could save a very large amount in tax, interest and penalties by using the Liechtenstein Disclosure Facility rather than the New Disclosure Opportunity. We estimate it could be a saving of over £2 million.”

All savers who open an account in Liechtenstein before March 2015 can take advantage of the disclosure facility.

However, those who initially opened an offshore account through a UK bank, or a UK agent of an overseas financial institution, would not be able to move their cash to Liechtenstein to take advantage of the loophole as HMRC would be able to see their “footprint”, Mr Berwick said.

A spokesman from HMRC said: “The terms of the agreement with Liechtenstein mean that UK residents with offshore investments not opened through a UK branch or agency of a financial institution can acquire an asset or an interest in asset in Liechtenstein and participate in the facility between the September 2 to the final compliance date of the March 31, 2015.”

Savers who do not come forward under either scheme risk being fined between 30 and 100 per cent of the tax they owe and could face prosecution.

Details of the loophole emerged days before an international meeting on tax evasion in Los Cabos, Mexico. The meeting, hosted by the Organisation for Economic Co-operation and Development, is set to increase the pressure on countries that are not making enough progress in making secretive accounts more transparent.