The Public Accounts Committee has decided to request information from Rehab and all State bodies that provide funding to it within the next fortnight.
It has decided to request that former Rehab chief executives Angela Kerins and Frank Flannery indicate within the next two weeks if they are willing to appear before the committee.
PAC said it will seek compellability powers from another Dáil committee if all of the parties involved do not provide the information or indicate if they will attend.
The committee is seeking further information on a number of issues including salaries, pensions and consultancy work.
Rehab received €95m from the State last year.
PAC Chairman John McGuinness said this evening that the committee needs "compellability powers in order to get full answers".
He said: "Public accountability demands that we get answers in terms of how that money was used every year.
"We now need to establish, in respect of each public body, the level of information each has and the extent to which they can disclose that information in a voluntary capacity."