KiwiSaver investors could pay as much as 31.6 per cent or as little as 4.9 per cent in fees depending on which provider they choose, according to the Commission for Financial Capability.
Over time this could result in significant costs.
According to estimates by the commission, a person joining KiwiSaver with a balanced fund at age 20 and retiring at 65 could pay as much as $56,200 over that period if they were with the most expensive provider.
That would fall to just $11,600 in fees if they selected one of the cheapest.
Broken down further, it equates to $1248 or $257 a year.
The marked difference in fees has sparked calls for people with KiwiSaver funds to check whether they are getting value for money, with one financial expert saying higher fees do not automatically equate to higher returns - and in some cases the opposite is true.
It comes after regulator the Financial Markets Authority released guidance to fund managers and their supervisors over fees amid concerns KiwiSaver members are not getting good value for money.
But some KiwiSaver managers say there won't be any major shift in fees until the regulator takes action against a provider.
Last year's annual KiwiSaver report by the authority found Kiwis paid $538.9 million in fees in the year to March 31, 2020 - up 12.3 per cent on the previous year. That was despite investment returns being down 122 per cent over the year.
The founder of the company that charged the highest fees said its ethical Islamic-approved funds were managed daily and had performance growth of 24 per cent in the last financial year.
The provider with one of the lowest levels of fees said banks held the biggest market share and, in his view, had no incentive to offer lower fees.
Figures provided to NZME from the Commission for Financial Capability calculated on its Get Sorted website for a balanced fund from the age 20 through to 65 estimates the highest KiwiSaver fees could cost $56,200 over that period if you are with Amanah Growth Fund, the AMP Global multi-asset fund would incur $52,700 in fees and the Nikko balanced fund $44,100.
The lowest were the Simplicity KiwiSaver Scheme balanced fund at $11,600, Juno KiwiSaver Scheme balanced fund at $12,300 and BNZ KiwiSaver Moderate Fund at $21,800.
ANZ was the largest KiwiSaver provider and had three balanced funds, and those fees were estimated at $32,400 to $32,700 over the same period.
According to the Financial Markets Authority, there are 29 registered KiwiSaver providers open to the public. Its latest figures show the banks had about two million members, while other providers had 1.02 million members.
Commission for Financial Capability personal finance lead Tom Hartmann said savers paid a professional team to invest their money through KiwiSaver but higher fees did not always result in higher returns.
He said providers had different styles of managing - some were more hands-on while others would invest funds to track in index, which was more automated.
''Some fund managers will do all the trading themselves and will trade more often to try to outperform the index. This approach is generally more expensive.''
Fees were usually a percentage of the amount of money being managed, or were a flat fee and unlike car payments, were taken out behind the scenes.
''In your account, all you are seeing is the funds going up and down. But all the while fees are being taken out typically on a monthly basis."
Often fees were represented in tiny percentages that did not look like a big deal, he said.
''The key is that you really need to make sure the fees are reasonable ... because they make a big difference.''
Amanah Growth Fund founder Brian Henry said its fees were accepted by the FMA as reasonable and it did everything ''in house''.
Amanah was able to charge an extra percentage of fees because of the nature of its ethical mandate and the degree of supervision it had to maintain in order to comply.
''We actually have to check our mandate daily. We are an Islamic-approved fund and the only one in New Zealand so we are a fund where strict Muslims and Christians can invest with us and know that we will meet their ethical requirements.''
That meant Amanah did not invest in any interest-based products, including mortgages and the banks.
''So at the moment we have invested solely into US-listed equities because that is the only place in the world that we can get sufficient disclosure.''
Last year, Amanah had 24 per cent growth and this financial year was likely to be 11 per cent, he said.
Juno KiwiSaver founder Mike Taylor said it was a purely digital offering and its investment team selected the investments directly.
It launched in 2018, had about 14,000 members and was growing by 1000 members a month.
''That means we don't charge percentage fees, we charge dollar fees so it's easy to understand. We're about delivering value for the consumer, low fees and active returns.''
Data from its website revealed balance fund returns of 20.9 per cent in 2020.
Taylor said, in his view, the major banks had the biggest market share and had no incentive to lower fees.
''KiwiSaver is very profitable for them.''
An ANZ spokeswoman said it was an active manager and fees were only one consideration.
''It's also important to look at a fund manager's ability to deliver long-term investment returns after fees.
''We generally utilise a higher level of decision-making, research and analytics, with an expected return greater than the index, so fees charged are typically higher than a passive manager.''
Over the last year, the ANZ KiwiSaver Balanced Fund had a return of 20.31 per cent, after the annual fund charge, and before tax and membership fees.
The KiwiSaver market has seen some recent low-fee entrants being quite successful, which showed healthy and vigorous competition in the market, she said.
''Furthermore, while the Australian-owned banks may have a large market share, we all offer below-average to average KiwiSaver fees.''
McKenzie Financial Services director Alison McKenzie said it was sensible to get unbiased advice.
She said often people's eyes glazed over when it came to talking about KiwiSaver.
''But because it's coming off your pay they don't always think it's important but it's huge. You also need to make sure you are in the right fund for your risk profile.''
An FMA spokesman said consultation on its guidance on KiwiSaver fees and value for money closed in December.
The guidance established the FMA's approach to providers' ongoing obligation to ensure their fees are reasonable and key principles for demonstrating whether KiwiSaver and other managed-fund fees are providing value for money.
In 2018, it also became mandatory for KiwiSaver providers to show their fees in dollar amounts in individual members' annual statements.
''This helps KiwiSavers to discover whether there's a good relationship between the amount they're paying in the fees and the amount that was delivered in returns for those fees.''
He said in the first instance, FMA advocated KiwiSaver members had a good conversation with their provider and were informed about what was going on with their investment.
''We want people to use comparison tools and consider shopping around for better value. You need to be able to ask questions of your current provider and see if you might have had a better experience with a different provider, if that is the case you can always walk away.''
Online KiwiSaver tools
• KiwiSaver Fund Finder providers offer hundreds of funds. How do they compare? https://fundfinder.sorted.org.nz/
• KiwiSaver fees calculator. Forecast what you're likely to be charged in KiwiSaver fees in various funds. https://sorted.org.nz/tools/kiwisaver-fees-calculator
• KiwiSaver savings calculator. How big could my KiwiSaver balance be? https://sorted.org.nz/tools/kiwisaver-savings-calculator