Michael Collins TD has announced that he is to resign from the Fianna Fáil Parliamentary Party following revelations that he is on a list of over 400 tax defaulters.
However, the representative for Limerick West TD still intends to hold his Dail seat.
The revelation is the latest to trouble Irish Prime Minister Bertie Ahern and his party.
In a statement, he said he was deeply embarrassed by the Revenue Commissioner's disclosure that he had made a settlment for a total of O130,602.
Mr Collins said he deeply regretted having the liability but that it predated his election to the Dail.
On Friday, the chairman of Fianna Fáil's Standards in Public Life Committee, Mr Seamus Kirk, said he would look at whether Mr Collins had broken party regulations.
Meanwhile, another Fianna Fáil is coming under pressure to resign after confirming that he knocked down a woman while driving under the influence of alcohol.
Dublin North deputy GV Wright responded to a media report by admitting that he had failed a breath test following the accident in Mountjoy Square in Dublin last week. Gardai police are investigating the incident and Mr Wright is expected to face drink-driving charges.
In a statement, Mr Wright said he was involved in the accident that led to the injury of a pedestrian on Thursday.