On the face of it, the KiwiSaver numbers look impressive.
Now in its tenth year, KiwiSaver has attracted 2.6 million New Zealanders, with an average of 400 people joining every day.
The biggest providers are now managing billions in KiwiSaver funds on behalf of their members.
But the Commission for Financial Literacy's investor education head, David Boyle, says the big numbers are masking some serious issues.
More than 1 million KiwiSavers are not contributing regularly to their funds - and that number is growing - and less than half of eligible KiwiSavers are putting in the $1042 a year needed to get the full $521 tax-free payment from the government. That's more than $300 million in unclaimed cash every year.
For someone in their 20s entering the workforce today, the member tax credit can add more than $20,000 to their retirement savings.
And while KiwiSaver has been successful beyond its creators' wildest expectations, there are still 22 per cent of working age adults who are not enrolled in the scheme, says Boyle.
"It's a bit like a duck on the water - it looks nice and flat on the lake but there's a lot of turbulence underneath and a lot of underlying currents that, if those trends continue, could have a material impact on people's wellbeing if they don't get on top of some of this stuff."
Boyle says a key cause of non-contribution is changes to employment conditions.
"It's not being talked about a lot, but people are moving from wages and salaries to contracts, for example," he says.
What people don't realise is that when they move to a contract, they are no longer automatically making contributions to their KiwiSaver fund and their employer is no longer chipping in their share, Boyle adds.
He says the number of total remuneration employment packages - where the employer contributions are built into the salary offer - may also be driving up non-contribution, because staff feel they are paying the contributions themselves.
He says that may part of the reason for the number of people taking contributions holidays, generally at the default length of five years.
It's a bit like a duck on the water - it looks nice and flat on the lake but there's a lot of turbulence underneath and a lot of underlying currents.
Originally designed to provide an option for people who need to take a break from KiwiSaver contributions to redirect funds to other areas, it has now become the norm for more than 100,000 KiwiSavers.
The break from savings is often extended once people hit the five-year mark, says Boyle, with many unlikely to be aware of the future cost to their financial wellbeing.
"Those things are having quite an impact I think and they are genuinely, with the numbers that are coming out, probably some of the leading contributors to some of those trends that we are seeing."