Savers who have stashed money offshore and failed to pay tax on the interest have been given a second chance to avoid massive penalties for doing so.

HM Revenue and Customs today said that it was launching a second "amnesty", allowing savers who come forward by March next year to pay the tax they owe plus an extra 10 per cent penalty.

Those who have failed to declare any income from overseas, such as second home owners who rent out their properties, can also take advantage of HMRC's 'disclosure regime'.

People who don't declare their offshore savings accounts or income face penalties of up to 100 per cent of tax owed and could face prosecution.

Savers with offshore accounts must pay tax on the interest they earn even if they do not bring the money back into the UK.

The initial disclosure regime, which closed in 2007, raised £400 million after 45,000 savers came forward.

At that time, HMRC had obtained details of all Britons holding money offshore from five major banks.

Those who were contacted by HMRC at the time but have yet to pay their tax bill can now do so with a penalty of just 20 per cent, HMRC said today.

Experts suggested that HMRC's resources were stretched as they did not have the time to chase up every non-payer.

Ronnie Ludwig, partner in the private wealth group at Saffery Champness said:

“Some of the terms offered demonstrate just how stretched HMRC is. It is surprising that even those written to under the last amnesty will be offered a chance to come clean. The amnesty also demonstrates HMRC’s grave need for cash."

Accountants also warned that offshore savers with complicated tax affairs could struggle to get help with their disclosures.

Andrew Watt, managing director at Alvarez & Marsal, a tax advisor, said: "The HMRC has picked the worst possible time of year to offer a tax amnesty...Accountants are usually very busy in December and January, when the majority of disclosures will be made. This may lead to a lack of capacity from many accountants to deal with the NDO," he said.

Since the last tax amnesty in 2007, HMRC has contacted hundreds of smaller banks and collected information on thousands more British savers. Accountants say the move could affect as many as 100,000 savers at 500 UK and foreign-owned banks and building societies.

Dave Hartnett, HMRC Permanent Secretary for Tax, warned that there were unlikely to be any more "amnesties".

“I know there are people who regret not taking advantage of our Offshore Disclosure Facility (ODF) in 2007 which focused primarily on the customers of five large banks.

Now everybody who has not paid the tax they should in relation to offshore accounts or assets has this New Disclosure Opportunity to pay what they owe with penalties on more favourable terms than normal," he said.

“This will be the last opportunity of its kind.”

Paul Roberts, Head of Tax Investigations at Grant Thornton, says, "Tax evaders who knowingly avoided disclosing their assets under the initial 2007 Offshore Disclosure Facility (ODF) in the hope they would not be caught are likely to be feeling the heat now."

"In some extreme cases, individuals could face penalties of up to 100 per cent of the tax due and in exceptional circumstances, a criminal investigation could follow. If any taxpayer in this situation receives a letter from their bank, they should consider taking advantage of the NDO or face serious consequences," says Roberts.

Chas Roy-Chowdhury, head of taxation at the Association of Chartered Certified Accountants (ACCA) , says: "Given the Revenue has limited resources it is much more sensible, as well as fairer, to target out-and-out tax evaders in this way, rather than pursue law-abiding individuals who may have made a small mistake in their tax return."