Bertie Ahern has flatly denied ever receiving a corrupt payment throughout his career and said he "never put himself before the public good".
He said he had "done no wrong and wronged no one".
He said he "would not allow issues of relating to his own person to dominate the body politic" and would tender his resignation to President Mary McAleese on Tuesday, May 6.
The Taoiseach has said he felt privileged to have served the country since he was elected leader of Fianna Fáil in 1994.
In a voice shaking with emotion, the Taoiseach said he was very proud of his contribution to peace and prosperity on the island and "humbled to have been entrusted" with the office of Taoiseach.
The Taoiseach said he had taken great solace from people's prayers and Mass cards through his recent difficult months.
He said he regretted any "confusion and worry" caused by his financial affairs and said he looked forward to "comprehensively dealing with matters at the tribunal and robustly refuting (any) imputations against him".