Almost 1.2 million people have joined the KiwiSaver retirement savings scheme since it started two years ago, Revenue Minister Peter Dunne says.
There was a 54 percent increase in people joining in the second year, he said.
The strong uptake by young people, aged between 19 and 25, was "particularly notable", Mr Dunne said.
In the year to June, $2.1 billion was collected from members, employers and the Crown.
KiwiSaver enrolments were growing slower than previously, which may be due to uncertainties in the economic environment, Mr Dunne said.
Membership was expected to plateau at 1.4 million, 200,000 more than at present.
Most of those who had joined KiwiSaver since April, when the minimum contribution rate was lowered to 2 percent of income, were putting in at the minimum rate.
Those who joined before April were likely to have remained at their previous level - 4 or 8 percent.
The economic recession meant more people were taking contribution holidays, Mr Dunne said.
It was too early to say whether KiwiSaver contributions were new or re-directed savings, he said.
KiwiSaver would be annually evaluated until 2012 to monitor the introduction and uptake of the scheme.
