Stats NZ has been giving away free Warriors tickets and food vouchers to coax people into completing the Census.
But it cannot say exactly how much it has spent on incentives as the deadline to fill out the forms approaches.
Its target is 90 percent of the population, but the completion rate is currently only 86 percent - about 4.5 million people.
The deadline is looming this Wednesday. Census and collections operations deputy chief executive Simon Mason believes there some distrust around filling out the forms.
