Moves to compel Brian Conlan -- the former CEO of the Central Remedial Clinic -- to give evidence at the Dail's Public Accounts Committee (PAC) will take several months to be realised.
Mr Conlan resigned this week ahead of the committee's hearings and has said he will not appear as part of a CRC delegation later today.
The committee is seeking answers as to how senior officials at the clinic were paid the controversial and unsanctioned top-up allowances.
However, any formal request to compel Mr Conlan would have to be approved by another Dail committee, which has never met.
But whether Mr Conlan is forced to give evidence will be determined by an existing request from the PAC to compel former SIPTU official Matt Merrigan over his involvement in a €4.4m HSE/SIPTU training "slush fund".
The PAC formally began its bid to compel Mr Merrigan to appear before it two months ago.
At a recent meeting, PAC chairman John McGuinness said he and the committee were "ready and waiting" to conclude its investigations into one of the most outrageous examples of excess and waste under social partnership.
Because of new Oireachtas Inquiry legislation, which was enacted into law during the summer, the Merrigan request has now been delayed to allow new standing orders to be drafted.
A sub group of the Oireachtas Committee on Procedure and Privileges (CPP) which has the power to grant compellability will then decide either to grant or refuse the PAC's request. That body has never met. Sources last night said a decision on the Merrigan case is now not likely until after Christmas.
Speaking to the Irish Independent at his home in Glasnevin, Mr Merrigan -- who retired from SIPTU on a pension last year -- said he has already given whatever response he is likely to give to the PAC and the Comptroller and Auditor General.
When asked would he concede to the compellability order, Mr Merrigan said he had no response.
Mr McGuinness said the power of compellability, of persons and documents, carries the same weight as a High Court summons -- if granted. Five senior staff at the CRC are still in receipt of top-up payments. Money raised by a charitable company had been used to top up the salaries of staff including its former chief executive. Former CRC chief executive Paul Kiely was on a state salary of €106,900 prior to his retirement, but this was supplemented by the clinic with a further €136,000, resulting in an overall pay package of more than €240,000.