The general election will be held on Saturday, 20 September, Prime Minister John Key has announced.
At his post Cabinet news conference at Parliament on Monday, Mr Key said he believes it is in New Zealand's best interests to give voters plenty of notice before election day.
Mr Key said he talked to the Governor-General, Lieutenant-General Sir Jerry Mateparae, on Sunday and advised the Cabinet on Monday morning.
He said he believed the elected Prime Minister should represent New Zealand at the G20 summit in Brisbane, Australia, on 15 and 16 November.
Mr Key said a number of world leaders have already expressed an interest in visiting New Zealand, which would not be possible in the middle of an election campaign.
He also wanted the announcement out of the way before his trip to China and the Hague next week and the royal visit of the Duke and Duchess of Cambridge and their son Prince George in April.
John Key said there should be plenty of time for post-election talks. "Well obviously, as the leader of the National Party, I'd hope that it's a very simple process because on election night we would know and hopefully we'd be in a position to put that Government together very, very quickly. But the reality of MMP is it could be a very complex environment."
Mr Key said it was unlikely that he would stay on as an MP if National loses the election.
The Labour Party's leader said on Monday the party is already in campaign mode and is ready to form a Government. David Cunliffe said the election is going to be about creating opportunity for all New Zealanders.
"Look, we would've been happy with a range of dates, we're happy to know it. We're already in campaign mode and we're aiming to give New Zealanders the opportunity for a new beginning."
Mr Cunliffe said Labour has been having regular meetings with the Green Party, and the next Government will be a coalition.