The Northern Ireland Assembly has been told that the DUP's Iris Robinson has formally resigned her seat as a representative in the Strangford constituency.
The announcement was made by the Speaker William Hay.
Shortly after Christmas Mrs Robinson announced she would be stepping down from all public offices having suffered mental illness.
It then emerged that she had obtained money from two property developers to help her teenage lover to open a cafe.
Her husband Peter Robinson has temporarily stood down as the North's First Minister but remains as DUP leader. The party will now have to nominate a replacement for Mrs Robinson.
Meanwhile in south Belfast, the SDLP's Carmel Hanna has formally resigned as an MLA. Her replacement is due to be Conall McDevitt, a PR executive and former press officer for the party.
He was chosen at a convention before Christmas and it is expected he will take his seat within the next fortnight when the formalities have been completed.