Changes for default KiwiSaver funds coming into force on 1 December include a trimmed list of providers and default funds changing from conservative to balanced.
A default member is someone who has signed up to KiwiSaver but not made an active choice about where to invest and has been allocated a default provider by Inland Revenue.
Among the changes, default fund members will have their savings moved into a balanced fund from the existing, more defensive, conservative fund.
The list of providers will drop from nine to six, they will charge lower fees and will not invest in fossil fuel production or illegal weapons.
Financial Services Council chief executive Richard Klipin said the balanced fund was more aggressive and took advantage of the ups and downs of the share market.
He said people on default funds should not worry but encouraged everyone to make sure the changes were right for them.
"December 1 marks a really important change for KiwiSaver.
"If you're a default member, then it's possible your provider has changed and that's all being taken care of for you."
Klipin said KiwiSaver members who were happy about their investment decisions, did not need to do anything either.
"If you are one of the impacted KiwiSaver members, the IRD will have made contact with you," he said.
KiwiSaver remained an important part of how New Zealanders thought about wealth, saving for wealth and preparing for retirement, Klipin said.
The average KiwiSaver balance was $28,000.
"The earlier you take a really strong interest in your KiwiSaver the better," Klipin said.