The Mahon Tribunal has set a date for the appearance of Taoiseach Bertie Ahern.
Mr Ahern is to appear over two afternoons on 26 & 27 July, just before the tribunal breaks for the summer.
His former partner, Celia Larkin, and Manchester businessman, Michael Wall, are both due to appear on 25 July.
Bertie Ahern is to be questioned about payments he received totalling at least £120,000 between 1993 and 1995.
Mr Ahern says the money came from savings, goodwill loans during his marital separation, and a £30,000 payment given by Manchester businessman Michael Wall.
But the tribunal has queried the £30,000 sterling payment in particular, saying there are no records of such a foreign exchange transaction on the day in December 1994 Celia Larkin claims she lodged the money.
Investigators have suggested it would correspond with $45,000.
The tribunal is investigating claims by Tom Gilmartin that rival developer Owen O'Callaghan told him he paid Mr Ahern a total of £80,000 in connection with the Quarryvale development.
Mr Ahern has described the allegations as false and malicious and denies ever receiving a dollar payment.
