NEW YORK (CNNMoney.com) -- It's tough enough to save for retirement without having to worry about hidden fees in your 401(k).
On Tuesday, the House Committee on Education and Labor will take up the issue, hearing testimony from experts who contend that some investors are unknowingly paying excessive retirement fees and slowing the growth of their nest egg.
With more and more employers shuttering their company pension plans, an increasing number of Americans have been relying on retirement vehicles like the 401(k) plan.
Roughly 47 million working individuals participated in a 401(k) plan in 2005, up from 7.5 million in 1984, according to The Profit Sharing/401k Council of America.
But because of weak disclosure rules, many workers are often poorly informed about all the potential fees they face, according to prepared remarks by experts, obtained ahead of Tuesday's hearing.
Over 80 percent of 401(k) investors are not aware of how much they pay in fees, according to a recent report published by United States Government Accountability Office.
Workers have seen their account balances penalized due to excessive fees by an average of 15 percent over the past 20 years, according to one expert set to speak before members of Congress Tuesday.
"We have to ask whether all these fees are necessary, and we have to examine whether they are undermining workers' retirement security," said California Congressman George Miller, chairman of the House committee.
According to prepared remarks by one independent pension fiduciary who will appear at Tuesday's hearing, 401(k) participants face as least seven different hidden fees, which cover everything from brokerage costs to trading fees that investors incur when they fiddle with their portfolio.
In some instances 401(k) participants are forced to pony up for services they may not even receive.
And those fees can add up quickly.
Take an investor who makes a $150 contribution per pay period to his or her existing $30,000 401(k) account balance. Assuming a rate of return of 8 percent over 25 years, the investors who has to pay just 1 percent in annual fees, will sacrifice $85,000 to fees by the time they retire.
Often times it's workers at smaller companies who end up getting stung the most by hidden fees, according to Stephen Butler, president of Pension Dynamics Corporation, who is scheduled to speak before lawmakers Tuesday.
Smaller firms are not always savvy enough when it comes to picking a retirement plan, says Butler, and its workers can end up paying up to 100 times more for the exact same services that a Fortune 500 firm receives.
One solution offered by experts such as Butler include a national standard disclosure form that would outline the amount an investor would have to pay in dollars and compound earnings over 10 and 20 years based on average fees charged to participants.
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