Members of the Public Accounts Committee are to probe Rehab executives tomorrow on their expenditure.
Rehab received €82m in State payments last year.
It is understood that members have been informed that they must stay within their remit and probe issues around payments from the Health Service Executive, Solas and payments under the Charitable Lotteries fund.
Legal representatives of Rehab informed the parliamentary legal adviser today that they are appearing before the committee on a voluntary basis and they would not be in a position to discuss areas that did not fall within the committee's remit.
Members were told they may have to limit their questions to accounts audited by the Comptroller and Auditor General.