The Office of the Revenue Commissioners has announced that it has identified 21,500 more bogus non-resident accounts with Irish addresses.
Revenue said that many of these accounts will have more than one signatory, and it estimates as many as 40,000 people may be involved.
The total number of non-resident accounts with Irish addresses that have been uncovered is now nearly 35,000, involving up to 70,000 people.
The discovery of the huge number of accounts was made upon investigation of thousands of documents received from a variety of financial institutions on foot of a High Court order.
Thousands of people will now receive letters demanding full payment of unpaid taxes, interest and penalties before March 27th, or face possible prosecution.
The names and addresses of all people whose settlements exceed €12,700 will be published.
Around 30,000 people were sent letters last October, resulting in over €100 million being paid to Revenue.
A number of cases where letters sent in October were unanswered by the December deadline are now being investigated with a view to instigating prosecutions.
To date, €119 million in back taxes have been paid since the Revenue introduced a voluntary disclosure deadline in November 2001.
