Rehab has provided further information to the Public Accounts Committee on a number of issues that members were seeking to be clarified.
One response deals with why former Rehab board member Frank Flannery and the Rehab remuneration committee were not present at the committee two weeks ago.
In the correspondence, Rehab states that it was discussed with them and it was felt the best people to attend were those who ultimately did.
On Mr Flannery's consultancy work for Rehab, the letter states that his fees are disclosed in consolidated accounts.
It also outlines a wide range of activities that he carried out, including lobbying.
The committee had also sought information on Mr Flannery's pension.
In reply, Rehab said that without the consent of the individual they are "precluded from providing the information".
The letter also states that Chief Executive Angela Kerins does not intend to provide any further information on her remuneration. She had already disclosed her salary.
Rehab also provided information on a company that imported material for Rehab to assemble coffins.
Ms Kerin's husband, brother and Mr Flannery were directors of the company but her husband later resigned his directorship.
Independent TD Shane Ross this evening said trying to get information out of Rehab was like trying to pull teeth.
The committee is expected tomorrow to set a date for the appearance of Mr Flannery and to seek further information.
Flannery insists he is not at odds with PAC
Mr Flannery, who is also a former Fine Gael strategist, has said he is anxious to deal with and correct "the misconception that a substantial impasse has arisen" between himself and the Public Accounts Committee.
In a letter from Mr Flannery to the PAC, seen by RTÉ News, Mr Flannery said he will respond to the committee when he receives a direct invitation and knows the agenda.
He said that he has not received any communication from the PAC, despite numerous reports and broadcast interviews with members of the committee.
Mr Flannery asked that the committee communicate with him at his home address so that he can deal with matters in the first instance in writing.
The letter states: "I understand it is the normal practice of the committee to set out the points it wishes to discuss in terms of the committee's role in reviewing public expenditure matters."
It has emerged that Minister for the Environment Phil Hogan held a meeting with Mr Flannery and other members of the Forum on Philanthropy in July 2012, according to a record of the meeting released to RTÉ's This Week.
The Irish Times revealed earlier today that Mr Flannery did unpaid work for the forum, but was paid €60,000 per year to promote a number of the forum's tax reform initiatives by another group, Philanthropy Ireland.
Mr Hogan was reportedly critical of PAC Chairman John McGuinness for what he described as a focus on the charity sector work of Mr Flannery.
According to records seen by RTÉ News, Mr Hogan met Mr Flannery on 4 July, 2012 in Leinster House to discuss the work of the Forum on Philanthropy.
Mr Flannery was hired by Philanthropy Ireland as a consultant in the middle of that year to promote the forum's tax reform proposals aimed at boosting the income of charitable trusts and foundations.
Mr Hogan's diary shows that he held formal meetings with Mr Flannery a total of six times between July 2012 and the following March, including once with Taoiseach Enda Kenny.
However, the meeting on 4 July, 2012 is the only one in which a subject for discussion was recorded.
Mr Flannery has come under scrutiny in recent weeks for his work as a lobbyist for members of the charity sector, while also acting as a senior strategist with the main government party.