A by-election to fill the Mt Albert seat left vacant following the resignation of former Prime Minister, Helen Clark, will be held on 13 June.
The Prime Minister, John Key, announced the date on Monday, following advice from the Chief Electoral Officer.
Both National and the Labour Party have begun their candidate selection process, as have ACT and the Green Party.
Nominations will close on 19 May.
Mr Key says it has been a very safe Labour seat, but he will put some effort into campaigning.
He says to the best of his knowledge his National Party has never held the seat.
National's two main contenders are list MP Melissa Lee, or the National's unsuccessful candidate for Mt Albert at last year's general election, Ravi Musuku.
The final selection for National's candidate will be made on 4 May.
Labour is yet to select its candidate.
Ms Clark had held the Mt Albert seat for Labour since 1981.
The former Prime Minister is now at the United Nations.