Expenses claimed by Cork North-Central TD Dara Murphy cannot now be investigated after he resigned his Dáil seat.
Mr Murphy had come under fire after it was revealed that he has claimed his full Dáil salary and expenses over the past two years, despite being largely absent from Leinster House.
Taoiseach Leo Varadkar told the Dáil that Mr Murphy would cooperate with the Oireachtas Ethics Committee or the Standards In Public Office Commission (SIPO) if requested.
However, neither body are now permitted to investigate a complaint made about Mr Murphy as he is no-longer a sitting member of the Dáil.
Mr Murphy formally resigned his Dáil seat just minutes after voting against a motion of no-confidence in Housing Minister Eoghan Murphy on Tuesday night.
Fianna Fáil leader Micheál Martin said Mr Murphy, who takes up a €150,000 job with the European Commission from today, had "effectively became an absentee Teachta Dála while still drawing a full salary".
He accused him of "neglecting" his constituents and should have resigned in 2017.
As well as retaining his Dáil seat, Mr Murphy had been working as a election campaign manager for the European People's Party (EPP).
Raising the issue in the Dáil, Mr Martin said: "The reality is that Dara Murphy should have resigned at the end of 2017 because since he took up office with Fine Gael grouping in Europe, the European People's Party, EPP, his parliamentary input has been reduced to near zero."
The Dáil heard that Mr Murphy had not spoken in the Chamber since December 7, 2017. He asked a total of five parliamentary questions in 2019 and only two in 2018 and only attended the Committee on Public Petitions once during the same period.
Mr Martin said: "I invite people to compare that record to that of his three colleagues in Cork North-Central. That behaviour reflects total disengagement from the Dáil.
"The people of the north side of Cork elected him to represent them. For the past two years he did not do that. The people of the north side of Cork were neglected by him, and that was endorsed by the Taoiseach and the Fine Gael Party.
Responding, Leo Varadkar said the TD was still responsible for looking after his constituency, through his constituency office in Cork, and being here as a Teachta Dála and Member of the Dáil during his time as EPP campaign director.
"The record shows that he was here for 120 days last year, including approximately 40 sitting days, and voted on occasions. He is not the only Member of the House to have another job and other employment.
"It is not permitted for Government Ministers to have other jobs or employment, but it is permitted for Teachtaí Dála to have other jobs or employment and some members of the Fianna Fáil front bench have other jobs and employment," said Mr Varadkar.