The deal to allow bogus non-resident bank account holders six months to declare any taxes owing has been criticised as a ‘sweetheart’ deal by SIPTU.
Last night the Taoiseach, Mr Ahern, denied he was introducing a tax amnesty.
But SIPTU general president Mr Des Geraghty said: "A rose by any other name still smells the same. And this one stinks."
He said: "Inequitable tax reductions were now going to be delivered to criminal tax evaders.
"We demand that the full rigour of the law should be applied and that all bogus non-resident account holders should be named and shamed."
The Worker’s Party of Ireland described the tax arrangements as "another charter for cheats".
Councillor Mr John Halligan from Waterford said the move was another example of one law for the rich and another for the working class.
But the deal of voluntary disclosure arrangements was welcomed across the board in theDáil, with the Government, Fine Gael and Labour all describing it as a sensible approach to tax collection.
"The Committee of Public Accounts asked the Revenue Commissioners to examine these issues and come back with what they believed was the best solutions to the problems. They have done that," the Taoiseach said.