Finance Minister Bill English is playing down a drop in KiwiSaver membership since the Government scrapped the $1000 kickstart payment in the May Budget.
Latest monthly figures from Inland Revenue show the number of people signing up is the lowest in more than a year, and fewer people under the age of 18 now belong to the scheme.
Mr English said some reaction was expected, but he did not expect it to have much impact long-term.
"The kickstart only applied to a smaller and smaller group of New Zealanders who aren't in Kiwisaver and only get it once they go in.
"So the sweetener that matters is the employer contribution and the Government subsidy and those remain intact."
Mr English said membership rates had been slowing because a large proportion of people had already signed up.
But the Labour Party said the Government's scrapping of the $1000 kickstart payment had led to a massive drop in people signing up for KiwiSaver.
Labour's finance spokesperson, Grant Robertson, said it was going to make a huge difference long-term.
"There's actually now a net decrease in the number of people aged under 18 in this scheme, because so few of them have actually enrolled.
"We've seen a 30 percent drop in new enrolments compared to the monthly average previously.
"This has made a significant difference to the number of new Zealanders who have now got into KiwiSaver."