Former chief executive of the Central Remedial Clinic Brian Conlan has agreed to appear before the Public Accounts Committee in early January.
Mr Conlan made contact with the Committee this afternoon and confirmed that he will give evidence in early January.
Committee chairman John McGuinness said Mr Conlan's evidence in the way remuneration packages were offered to certain staff in the voluntary sector was important.
He said: "We want those voluntary bodies to get on with providing the vital services they are contracted to do.
"However, they need to become compliant in terms of remuneration as, at present , this is having a negative impact on their ability to raise private funding through charitable donations."
Taoiseach Enda Kenny has said the controversy at the CRC has been a shock to so many people who give money in the understanding it is going for children and adults who need care and facilities.
Mr Kenny said he understood the board had gone off to consider their positions.
He said the PAC's analysis and engagement with the board yesterday left nobody in any doubt about what should be done.
Meanwhile, Minister for Justice Alan Shatter has said the CRC revelations have given an insight into some financial dealings that were completely and highly inappropriate for any charitable organisation.
He also said he expected to bring in new legislation regulating the charity sector next year.
Earlier, there were further calls at the PAC for the resignation of the entire CRC board.
Deputy Kieran O'Donnell said the continuance of the present members of the board cast a cloud over, what he described as, the fantastic work that the staff of the CRC did.
He said it was also damaging fundraising potential.
Some members of the PAC demanded resignations from CRC board members yesterday.
However, Mr McGuinness said the board should not resign yet, because it would leave a "vacuum" while the committee investigation was continuing.
He said the committee had shown its strength yesterday and "lifted the lid" on an area that was largely unaccounted for before.
Mr McGuinness urged the public to continue supporting charities while the work of the PAC was ongoing.
Minister for Health James Reilly said this morning that his department would use all powers available to it to ensure that public pay policy was adhered to.
Clarity sought on €660,000 payments
Independent TD Shane Ross has said Mater Hospital management would have to be called before the Public Accounts Committee to clarify the way it has used annual payments of €660,000 made to it by the Central Remedial Clinic.
In a statement last night, the Mater Hospital took issue with comments made to the Public Accounts Committee by former CRC chief executive Paul Kiely.
It rejected the suggestion by Mr Kiely where he referred to annual payments of €660,000 by the CRC to the hospital as having "no meaningful basis".
The PAC heard that the payment was for the administration of a pension fund that did not exist.
However, the Mater said this was not true, and that it looked after a pension scheme for 181 staff members of the CRC.
The hospital called on Mr Kiely to formally correct what it called an inaccurate reference.
Speaking on RTÉ's Morning Ireland, Mr Ross said it was imperative that the committee get clarity from the Mater on where the money went, how it was calculated and what it was spent on.
He said the issue remained a mystery and that the PAC would have to look at the Mater's accounts to see whether it accepted liability for the CRC pension fund and how it accounted for it in its balance sheet.
Meanwhile, the Health Service Executive is meeting the chairmen and a board member of each of the voluntary hospitals and agencies that receive HSE funding today.
It is presenting them with an annual statement detailing their obligations, which they will have to comply with by the end of the year and which will form part of their service level agreements with the HSE.