The KiwiSaver scheme could become more flexible if proposed changes go through, says the Commission for Financial Capability.
The Commission is reviewing retirement income policies and says the voluntary scheme could be improved with "a few tweaks".
Among the proposals are changing the levels of contributions that people can make, while keeping the employer contributions at 3 percent, and introducing an option to automatically increase contributions by a certain amount each year.
Other options include allowing people aged over 65 to join, and reducing the contributions holiday to a maximum of one year, rather than five.
The eight ideas on the shortlist:
Flexibility in contribution rates
The current fixed contribution rates are 3 percent, 4 percent and 8 percent. The employer rate would remain at 3 percent but employees would have the option of contributing other rates as well, perhaps up to 10 percent.
Automatic increase in contribution rates
Savers could choose to automatically increase their contributions by 0.5 percent or 1 percent each year, up to a maximum level.
Lower contribution rate for a limited time
Savers who are struggling could reduce their contributions to 1 percent or 2 percent for a limited period.
Providers would show the total dollar amount of fees paid
The exact amount of fees, in dollars, would be included on annual statements.
Reduced contributions holiday
Currently the maximum period you can stop contributions for is five years. That would be reduced to one, with the option to renew each year.
People over 65 can join
Currently only those aged under 65 can join KiwiSaver. This change would allow people over 65 to join, but they would not receive the government tax credits, nor would employers have to contribute.
One-off auto enrolment
An automatic enrolment day for those employees who are currently not in KiwiSaver, with an opt out option for those who don't want to join.
Multiple scheme membership.
Currently KiwiSavers can only belong to one scheme.
Changes need careful consideration
Commission spokesperson David Boyle said any changes need to be considered very carefully before they are made.
"People have told us that the jump from 4 percent to 8 percent is too big and they would like to have other choices. If that encourages people to contribute more to their retirement savings, then it's worth looking at.
"But there are also people who find 3 percent is too high and we wonder if a lower rate of 1 percent or 2 percent for a limited period would reduce the number of people taking contributions holidays and help more people get started."
KiwiSaver expert Mary Holm said the options were largely positive.
She was concerned allowing people to belong to multiple schemes would complicate a reasonably simple system, and would increase the fees savers paid.
But she said reducing the maximum contribution holiday was a good idea.
"There are too many people on contributions holidays now, once they've gone on for five years, it's a long time, they can go right out of the habit of being in KiwiSaver and of making those contributions.
"It's made it too easy to essentially opt out of the system."
And allowing for an automatic increase in contributions was also good.
"There's a lot of research that suggests if people are prompted to save more in the future they will do that more than if they are prompted to save now."
The options are open for consultation for several months. Anyone can have their say on the commission's website here.