The Christchurch East by-election will be held on Saturday, 30 November.
The sitting Labour MP, Lianne Dalziel, is leaving Parliament to contest the Christchurch mayoralty.
The last day for candidate nominations for the resulting by-election is 5 November, but some parties have already made their selections.
The Labour candidate is Poto Williams. Matthew Doocey will contest the by-election for National, and David Moorhouse will stand for the Green Party.
Mr Moorhouse, is a software developer, was the Green Party candidate in Christchurch Central at the last election. He won selection over the list MP Mojo Mathers, who had been a candidate in that electorate in the past.
Greens co-leader Metiria Turei says the decision was made by a five-person panel, and is not a slight against Ms Mathers.
Ms Turei says Ms Mathers will work with Mr Moorhouse on the by-election campaign
The Greens came a distant third in Christchurch East in 2011 and Ms Dalziel won the seat for Labour with a majority of 5334.
