HM Revenue & Customs (HMRC) has begun a fresh crackdown on tax evaders by targeting thousands of British-based savers who have failed to disclose offshore accounts.

A spokesman for HMRC said: “We are starting to send out letters to about 55,000 individuals in the UK. In the most serious cases, prosecution is likely to follow.”

The operation follows HMRC's legal victory last year that forced HBOS, Lloyds TSB, Barclays, HSBC and RBS to hand over details of more than 400,000 customers with offshore accounts. This was whittled down to 100,000 cases where the Revenue suspected that some UK tax was due.

Between April and July last year, 45,000 people came forward to give details of their non-UK savings, under the Offshore Disclosure Facility, which promised less harsh penalties for those who volunteered information. By agreeing to levy a penalty of only 10 per cent on top of the tax and interest due, HMRC succeeded in collecting £400 million.

The Revenue spokesman said: “We will now be contacting all those with offshore accounts who did not come forward under the ODF arrangements, or where there is a risk that the full amount has not been declared. We are also making additional inquiries where people appear to have undeclared tax liabilities but have not come forward.”

Manoj Anand, a senior manager at Tenon, the accountant, said: “We are aware that our local tax office has already sent out a number of letters to holders of offshore accounts and it seems this is happening at hundreds of tax offices across the country.”

He said that under the latest HMRC initiative, tax offices had been supplied with information about specific accounts, including their numbers.

Mr Anand said: “Taxpayers need to be aware that local tax offices are in possession of this information. A large number of inquiries are likely to be undertaken as a result. They should be aware that the Revenue may act outside its current powers in seeking information during these inquiries. Those with an undisclosed bank account are advised to seek specialist advice.”

Roy Maugham, a tax partner at the accountant UHY Hacker Young, said: “The latest initiative is targeting tens of thousands of people with offshore accounts and they should take it seriously. Those who think they may owe tax should make an early disclosure.”

In a sample study last year of 461 UK-resident taxpayers who had not declared any foreign income, HMRC uncovered further tax liabilities in 118 cases (26 per cent) with an average figure of £16,000 per individual.

The HMRC spokesman said: “We would encourage all those people who are receiving interest from offshore accounts to declare it immediately, rather than wait for us to get in touch after we have traced them from account records.”

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