In an article for the Sunday Independent he said he was resigning from Fianna Fáil – just days before the party’s National Executive was due to meet.
Mr Ahern, who led the party for 14 years, says in his article that the tabling of the motion to expel him “deeply saddened” him.
It comes after the publication of the final report of the Mahon Tribunal.
In his article, Mr Ahern said the last thing he wanted to do was to be a source of political division in the party, which is why he decided to tender his resignation.
He stresses that this is a political decision, and not in any way an admission of wrongdoing.
The article reiterates his rejection of the Tribunal’s findings, and confirms he is considering options for vindicating his good name.
The full article is in tomorrow’s Sunday Independent.
There has been no comment from the party here in Co Donegal.