Bertie Ahern will tomorrow officially tender his resignation after 11 years as Taoiseach.
He will meet with President Mary McAleese after one of his final acts in office - the joint opening of the Battle of the Boyne site in Co Louth with outgoing Northern Ireland First Minister Ian Paisley.
The Taoiseach is to tender his resignation tomorrow
The 82-year-old Democratic Unionist Party leader is also due to step down later this month.
The Taoiseach will later travel to his now famous local pub, Fagans of Drumcondra, where he will mark the occasion with friends and neighbours, almost a week after his historic address to Congress.
Mr Ahern will be succeeded by current Tanaiste Brian Cowen on Wednesday when he will be nominated to the Office in the Dail.
Mr Ahern announced his shock resignation early last month amid mounting pressure over his personal finances, which are currently being probed by an anti-corruption inquiry.
Elected Taoiseach in 1997 and winning three successive General Elections for Fianna Fail, Mr Ahern was the country¿s second longest serving premier after party founder Eamon De Valera.
While denying any wrongdoing, the 56-year-old leader said he decided to hand over the party reins earlier than expected because he did not want the focus on his finances to create problems for the ruling party.
The Taoiseach will begin his final day in office by travelling to Co Louth to jointly open the €25 million Battle of the Boyne restoration project, which includes a visitor centre, with Mr Paisley.
Last year the two leaders met at the site where Mr Paisley presented the Taoiseach with an antique musket rifle used by one of King James¿ troops at the 1690 battle.
The symbolic ceremony is expected to be over by lunchtime and then Mr Ahern will travel the 30 miles south to Dublin to hand over his letter of resignation to President McAleese at around 6pm.
Mr Ahern, whose high points in office include the signing of the Good Friday Agreement in 1998 with former British Prime Minister Tony Blair, said yesterday he would continue to represent his Dublin Central constituency, but would decide in the future if he would run in the next General Elections.