The Taoiseach is to be asked why he counter-signed blank cheques drawn on the Fianna Fail leader's account in 1989 and how £25,000 was used for Mr Charles Haughey's benefit.
When the Dail meets tomorrow Mr Ahern will also be questioned on whether funds intended to pay for the late Mr Brian Lenihan's liver operation ended up in this account. He will also be asked about the origin - and use - of other highly sensitive party donations.
It is unlikely that the Taoiseach will correct the Dail record at this time, or explain his role in the unorthodox financial arrangements then in use within Fianna Fail.
Two weeks ago, Mr Ahern sought - and secured - written advice from the Moriarty Tribunal that he should not publicly explain his role in this matter until the confidential phase in the tribunal's work had been completed. On the strength of that he has declined to make any comment.
What is known is that a £25,000 cheque, drawn on a special AIB account in Baggot Street containing the State-funded party leader's allowance in 1989, was discovered last year in a Guinness & Mahon bank account under the control of Mr Haughey's financial adviser, the late Mr Des Traynor. It had been signed by Mr Haughey and counter-signed by Mr Ahern.
Discovery of the cheque led to discussions, last August, between the Taoiseach and the Tanaiste, Ms Harney. And it was agreed that it should be referred to the Moriarty Tribunal for investigation.
It is still the view of the Progressive Democrats that the Moriarty Tribunal is the place to deal with the matter, rather than the floor of the Dail.
In September 1997 Mr Ahern rejected efforts by Fine Gael and Labour to require the tribunal to investigate the operation of the Fianna Fail party leader's account under its terms of reference.
On that occasion the Taoiseach told Mr Dick Spring in the Dail: "Insofar as I could, with little available records, I am satisfied, having spoken to the people who administered the account, that it was used for bona fide party purposes, that the cheques were prepared by that person and countersigned by another senior party member."
Mr Ahern did not tell the Dail he was one of the members authorised to counter-sign the cheques - the other was Mr Ray MacSharry. Neither did he allude to the practice whereby he was asked to sign a number of blank cheques at a time.
Reliable sources have confirmed that large amounts of money - apart from the State-funded party leader's allowance - were moved through the account. It is understood these funds consisted of party donations personally solicited by Mr Haughey. Files in relation to this fund are understood to be missing from Fianna Fail head office.
Following his election as party leader, Mr Haughey dispensed with the services of Mr Des Hanafin as official party fund raiser and sought donations in his own right. Later, a twin-track fund-raising system appeared to develop in the party.
The Moriarty Tribunal is understood to be having difficulties in tracing the origin of funds in the account. And it is expected to investigate allegations that political donations designed to fund Brian Lenihan's liver operation in 1989 were paid into the account.
There is no record of payments being made from the special Fianna Fail party leader's account to the official Lenihan fund-raising account. The latter account was run by businessman Mr Peter Hanley, and the family was fully advised of the list of donors and the details of the account.
A Fianna Fail spokesman declined to comment last night and said these matters would be dealt with by the tribunal.