Voters in the Mana electorate have less than a week to enrol or update their enrolment details for the by-election in November.
Registrar of Electors Toni Weir says voters have until 20 October to return their voting cards to get on the printed electoral roll used in polling places and advanced voting venues.
People aged between 18 and 29 make up most of those not enrolled in the electorate near Wellington.
The by-election will be held on 20 November.
