Gina Hacker, AP
Brett Hacker, a photographer for a TV station in Kansas City, Mo., looks over his 401(k) statements.

Fees related to a 401(k) can cost a median-income household about $155,000 over a lifetime, according to a recent study by InvestingNerd.

Consumers can see all the fees they are charged in their annual prospectus statement, but few understand the fees or know what is a good deal and what is not. Of those surveyed, nine out of 10 underestimated the fees they were charged from the 401(k).

The most known fee is the expense ration, which measure’s the fund’s annual operating expenses. Different accounts charge different fees, but there is a general three-layer fee structure. Besides expense ratio, there are other mutual fund-level fees and plan-level fees.

Fund-level fees come from the cost of purchasing a fund and trading costs that come with the fund. The costs average about 1 percent of assets.

Plan-level fees come from the providers and administrators of the plan. An average cost is about .72 percent of assets. Expense ratio fees generally take the largest amount with 1.105 percent of assets.