The Revenue is expected to announce the size of the haul achieved from its offshore assets scheme next Tuesday.

The amount involved in the scheme - for which the final payment deadline was yesterday - is expected to be hundreds of millions of euro and there has been speculation that it could be as high as €1 billion.

The Revenue have already collected €150 million from investigations into a Bank of Ireland Jersey subsidiary and an Irish Permanent operation in the Isle of Man.

It emerged in the May exchequer returns that a further €150 million had already been paid by the end of last month to the exchequer in relation to the scheme.

This brings the total to €300 million, but considerable amounts are likely to have come in over the past couple of days.

In the months ahead the Revenue is expected to seek High Court orders that will assist them identify Irish residents with offshore bank accounts who did not avail of the scheme.

Yesterday was the closing day for making payments under the scheme. Persons who came forward and revealed the existence of an offshore asset, will not be identified or prosecuted. They also benefit from reduced penalties.

The Revenue would not comment yesterday as to how many people have availed of the scheme.

Qualifying persons had to make contact by March 29th and on that date the Revenue indicated that an estimated 15,000 had come forward.

A provision in the Finance Act 2004 allows the Revenue seek an order from the High Court instructing an Irish-based financial institution to provide information held by an associated bank or subsidiary bank outside the State.

It is expected the Revenue will later this year seek to use the provision to get lists of customers of offshore Irish banks who have Irish addresses.

These lists will then be compared with the names of those who have availed of the voluntary disclosure scheme, in order to identify those who have not come forward.

Tax practitioners yesterday said that despite a two-week extension, there had still not been enough time to process many of the disclosures.

Many cases involve elderly people and accounts going back to the 1980s. Practitioners said they are having difficulty getting the necessary information from the banks in time for yesterday's deadline.

"The Revenue has been very reasonable to date," said Mr Brian Keegan, of the Institute of Taxation in Ireland.

"If you don't have the necessary information and you explain your case and make a reasonable payment on account, I think it will be seen as a qualifying disclosure."

Mr Keegan said he believed that in many cases the cash lodged to the offshore accounts may have been after tax income, though the interest that subsequently accrued may not have been declared.

In other cases money that had been lodged abroad had since been dispersed or bequeathed, developments which created complex legal issues, he said.

Mr Frank Hussey, President of the institute and senior partner at LHM accountants, said he had a few clients for whom it was not possible to collect the necessary information by yesterday.

"There is anecdotal evidence that this is happening around the country." He said the Revenue was "not the worst" when it came to being flexible.

Persons who failed to come forward for the 1991 tax amnesty, which was compulsory, could avail of the offshore assets scheme.