HM Revenue & Customs (HMRC) is giving taxpayers with offshore investments more time to come forward under the New Disclosure Opportunity (NDO) or risk being investigated.

The New Disclosure Opportunity, announced in the April Budget, required taxpayers with undisclosed overseas income to first notify HMRC of an intention to disclose and then send in full details.

The registration deadline has been moved from Monday (30 November) to 4 January 2010 as it has acknowledged that some banks need more time to contact their offshore customers.

The NDO is the last such opportunity for taxpayers to obtain favourable terms when they tell HMRC about offshore investments that they have never disclosed in the past.

HMRC is currently receiving information from 308 banks in the UK about their offshore customers, which will be used to ensure that everyone pays the right tax.

Dave Hartnett, permanent secretary for tax of HMRC, said: “We know that some bank customers will not be contacted by their banks in good time for the original deadline of 30 November so in the interests of fairness we have decided to extend our deadline by a month to 4 January.

“I strongly urge anyone who has been hiding taxable assets offshore to go online and register. The NDO is voluntary but from the start of the New Year we will begin to investigate those who were eligible to use the NDO but instead buried their heads in the sand. Don’t let that happen to you.

“This is a great way to start the New Year – with the knowledge that your tax affairs are in order and the certainty that the penalty will be capped at 10 per cent.”

Gary Ashford, chairman of the management of taxes sub-committee of the Chartered Institute of Taxation (CIOT), said: “This is a sensible and realistic move which recognises the lack of time under the original deadlines.

“As we envisaged, there hasn’t been enough time to sort out all the information from the various banks. The new deadline should work, even if it might mean an uncomfortable Christmas for some taxpayers.”