The £176 million (€223.5 million) raised by the Revenue's voluntary disclosure scheme brings to almost £1 billion the amount of money collected in special schemes over the past 13 years.

The 1988 tax amnesty introduced by the then Haughey government brought in £500 million. The 1993 tax amnesty, brought in by the Reynolds Fianna Fβil-Labour coalition government, brought in £260 million.

The voluntary disclosure scheme for holders of bogus non-resident accounts, which yesterday was revealed to have brought in £176 million, is likely to have had implications for some people who availed of the 1993 amnesty, the most controversial of all the special tax schemes introduced.

The 1988 amnesty was introduced by the then minister for finance, Mr MacSharry, and was aimed at bringing in revenue at a time when the State's finances were in a very unhealthy condition.

People were able to settle outstanding taxes without interest or penalties. The scheme was so successful it led to a jump in the value of Government gilts.

The 1993 amnesty was much more controversial, not least because the first was supposed to have been a once-off event.

Under this scheme, introduced by the then minister for finance, Mr Ahern, persons who brought forward undisclosed income were able to settle for just 15 per cent of the tax due, and without paying any interest or penalties. At the time it was said the measure was aimed at "hot money" lodged abroad, though in the event the deal was available to those with money lodged domestically.

A second, surprising element of the scheme allowed people who were already in negotiation with the Revenue to avail of terms similar to the 1988 amnesty. (In other words, settle for the full amount of tax owed, but without interest or penalties.)

Among the entities to avail of this offer was the Goodman group, which the beef tribunal had discovered to be involved in a massive tax fraud. Though the group was involved in negotiations with the Revenue from 1991, it was able to avail of the 1993 amnesty as the negotiations had not been concluded by then.

Overall, £260 million was raised by the 1993 amnesty, with £193 million of this coming in under the 15 per cent scheme and representing £643 million in undeclared income.

It was a criminal offence not to avail of the 1993 amnesty. It was also a criminal offence to avail of the amnesty and not fully disclose all undeclared income. The maximum sentence involved was eight years imprisonment. For certain offences involving more than £100,000, a jail term was mandatory.

No prosecution has been taken under this clause, even though it is generally believed that many people who availed of the amnesty did not declare all their hidden money. They did so in order to get one of the powerful certificates which were issued to persons who availed of the amnesty and which make it very difficult for the Revenue to investigate their affairs prior to the date of the settlement.

In the Revenue's current inquiry into the Ansbacher deposits, it is known a few depositors have claimed they made use of the 1993 amnesty. The recent voluntary disclosure scheme includes an "amnesty" from prosecution for all those who had bogus non-resident accounts and who did not avail of the 1993 amnesty or who did so improperly. In other words, if they came forward under the disclosure scheme with a bogus non-resident account which had not been declared in 1993, they would not be prosecuted for not availing of that amnesty.

Possession of a bogus non-resident account gave people access to the voluntary disclosure scheme.

Once in they could settle all their affairs under the terms of the scheme, and not just the money lodged to the bogus account or linked to it. This opportunity did not exist for other tax dodgers who did not have bogus non-resident accounts. A 1994 survey by the Comptroller and Auditor General of 2,000 people who had availed of the 1993 amnesty found that 35 per cent had availed of the 1988 amnesty.