Your 401(k)’s default investment is costing you more than you realize—potentially tens of thousands of dollars over your working life. If your plan automatically enrolls you in a target-date fund or a conservative default option, and if your plan charges higher-than-average fees, the math is stark: a 0.50% annual plan fee alone can reduce a $100,000 portfolio by $157,000 over 35 years, according to retirement savings analysis. That’s not a market downturn or bad timing. That’s what happens when fees compound invisibly year after year. The problem starts with how most 401(k) plans are designed.
When you enroll, if you don’t actively choose an investment, you’re typically placed into whatever default the plan sponsor selected—often a target-date fund or a stable value fund. These defaults can range from well-managed, low-cost options to expensive, underperforming choices that your employer selected years ago and never reconsidered. Even small fee differences add up. A $25,000 balance invested at a typical 7% annual return grows to $227,000 over 35 years with low-cost funds, but only $163,000 with higher-fee alternatives—a $64,000 difference from fees alone. Understanding these defaults and their costs isn’t optional financial literacy—it’s the difference between retiring on your terms and retiring with significantly less than you expected.
Table of Contents
- What Are Default 401(k) Investments and Why Do They Cost More?
- How Much Are Fees Really Costing You? The Real Dollar Impact
- The Target-Date Fund Trap—Professionally Managed But Expensive
- How to Evaluate Your Plan’s Default and Take Control
- Hidden Fees Beyond Expense Ratios—Plan Fees and Advisor Costs
- The Abandoned Account Problem—Where $1.65 Trillion Goes
- The Industry Shift Toward Low-Cost Defaults and What It Means
What Are Default 401(k) Investments and Why Do They Cost More?
When you sign up for a 401(k), your employer chooses a default investment—the place your contributions go if you don’t manually select where your money should be allocated. This default is often a target-date fund (a fund that automatically shifts from stocks to bonds as you approach retirement) or, in some older plans, a money market fund or stable value option. The problem is that these defaults vary wildly in cost. The average 401(k) equity mutual fund carries an expense ratio of 0.31%, but many target-date funds charged 0.87% back in 2004. That gap has narrowed—target-date funds averaged 0.36% by the end of 2023—but averages hide the outliers.
Some plans still offer target-date funds or other defaults with expense ratios above 1%, charging participants 10 times more than a low-cost passive index fund. The fee difference seems small on paper—0.36% versus 0.08% (the average for passive equity funds)—but it’s compounded annually, and compounding over decades is devastating. When 61% of 401(k) plans use auto-enrollment with a default deferral rate of 4% or higher, and 67% of participants rely on professionally managed allocations like target-date funds, most workers are unknowingly locked into these fee structures from day one. They make their contribution, it goes to the default, fees are deducted each quarter, and they rarely revisit the choice. By the time they check their balance five years later, they’ve already paid thousands in unnecessary fees, and those dollars never had the chance to grow.
How Much Are Fees Really Costing You? The Real Dollar Impact
Let’s make this concrete. Imagine you’re 30 years old with $25,000 in your 401(k), and you have 35 years until retirement. Your plan’s average annual return is 7%. If your investments charge low fees—say, a 0.10% expense ratio through low-cost index funds—your $25,000 grows to $227,000. But if your plan defaulted you into a higher-fee option with a 0.50% or 0.75% expense ratio, that same investment grows to only $163,000. That’s a $64,000 difference created entirely by fees. For someone with a larger balance—say $100,000 at age 35—the 0.50% plan fee compounds into $157,000 in lost value by age 70. This calculation isn’t theoretical.
The U.S. Government Accountability Office studied 401(k) plans in 2023 and found that plans with expense ratios above 1% underperformed lower-cost peers by 0.5% to 1% annually. That doesn’t sound like much in one year, but over three decades, a persistent 0.5% annual underperformance (which is what you’re paying in excess fees) erodes returns significantly. A worker earning a typical 401(k) return of 5% to 8% per year is instead earning 4.5% to 7%—a nearly 10% reduction in total growth. The federal government has flagged this issue precisely because the impact is substantial enough to warrant attention. The limitation here is that not all plan sponsors actively monitor their default investments. Some plans inherited their fund lineups from years ago and simply never updated them. A default target-date fund that was competitive in 2010 might be expensive relative to newer alternatives in 2026. Without participant pressure or plan audits, funds can stay in place long past their usefulness, silently draining returns.
The Target-Date Fund Trap—Professionally Managed But Expensive
Target-date funds are designed to appeal to employees who don’t want to think about asset allocation. You pick a fund with your retirement year in the name—a 2055 target-date fund, for example—and the fund automatically becomes more conservative as you approach retirement, shifting from stocks to bonds. The concept is sound. The execution varies wildly. A well-managed target-date fund can be an excellent choice, especially for younger workers who don’t want to spend time rebalancing. But many 401(k) plans offer target-date funds with embedded costs that are hard to see.
A target-date fund with a 0.36% expense ratio might seem reasonable until you realize it’s a “fund of funds”—meaning it holds multiple underlying mutual funds, each with their own fees. Those underlying funds might average 0.20% to 0.30% each, so the total cost of ownership is actually 0.50% to 0.60% or higher. Meanwhile, a low-cost target-date fund from a firm like Fidelity or Vanguard might charge only 0.08% to 0.15%. Both are sitting in the same 401(k) plan, but one costs 3 to 6 times more than the other. The warning: because target-date funds are “set it and forget it,” many workers never look at the actual underlying funds or the embedded fee structure. A participant who chose a target-date fund in 2010 and hasn’t reviewed it since doesn’t realize that a cheaper alternative was added to the plan in 2018. They’ve been paying 0.45% when 0.12% was available—creating years of unnecessary losses that are already sunk into the past.
How to Evaluate Your Plan’s Default and Take Control
Your first step is to get a copy of your plan’s investment menu and fee disclosure. By law, your employer must provide this information—it’s typically on your plan’s website or in your participant handbook. Look for the expense ratio of your current default investment and compare it to the lowest-cost option in the plan. If the default is 0.40% and there’s a low-cost index fund at 0.08%, you’re looking at a 0.32% annual cost difference, which compounds into tens of thousands of dollars over a career. If your plan has multiple target-date funds—say, one from an expensive provider and one from a low-cost provider—the math strongly favors the lower-cost option.
Even if they have the same target allocation, the cheaper fund will outperform over time simply because less money leaves your account in fees. The tradeoff is minimal: you’re not sacrificing performance or quality by choosing the cheaper option. You’re capturing the same market returns, just with less leakage. If your plan’s cheapest options still seem high—above 0.25% for an equity fund, or above 0.30% for a target-date fund—you have grounds to contact your plan sponsor and ask why. Plans with 28 investment options (the average) have no excuse for not including at least one low-cost index fund. Many large employers have switched to low-cost index funds as their defaults specifically because participants complained about fees, and because the trend in the industry is unmistakably toward lower costs.
Hidden Fees Beyond Expense Ratios—Plan Fees and Advisor Costs
The expense ratio is only part of the story. Many 401(k) plans also charge administrative fees—charged at the plan level, not the individual fund level—to cover record-keeping, compliance, and customer service. These fees might be $50 to $300 per year per participant, depending on the plan. If your plan has 500 employees, those fees might add up to $150,000 annually, divided among participants. On a $100,000 balance, that could amount to 0.10% to 0.30% annually, on top of the fund expense ratios. Some plans also bundle in advisor fees—either direct advisor fees if the plan includes professional advice services, or implicit fees if the plan uses brokers or consultants who take a cut.
These are sometimes disclosed clearly, and sometimes buried in the fine print. The warning: these layered fees can push the total cost of your 401(k) well above 0.50% annually, even if the fund expense ratios look reasonable. A participant thinking they’re in a 0.35% target-date fund might actually be paying 0.35% fund fee plus 0.15% plan fee plus 0.10% advisor fee—totaling 0.60% annually without realizing it. The limitation is that many participants don’t have the power to change plan fees—those are set by the employer and the record keeper. But you can demand transparency. Ask your HR or benefits department to provide a full fee disclosure showing expense ratios, plan fees, and any other charges. If they can’t or won’t, that’s a red flag that your plan sponsor isn’t taking fees seriously.
The Abandoned Account Problem—Where $1.65 Trillion Goes
A parallel issue affecting many 401(k) workers is abandoned accounts. When you leave a job, your 401(k) stays with that plan unless you roll it into an IRA or your new employer’s plan. Some workers leave their old 401(k)s where they are, simply forgetting about them. As of 2023, there were 29.2 million abandoned 401(k) accounts holding $1.65 trillion in assets.
Many of those accounts are still being charged plan fees, advisor fees, and potentially high investment fees, eroding balances that the worker isn’t monitoring or even remembering they have. This is especially damaging if the abandoned account is in an expensive plan or a small employer plan with high per-participant fees. A $50,000 abandoned balance in a plan charging 0.75% annually is losing $375 per year, simply sitting there. Over a decade, that’s $3,750 plus lost growth on that $3,750. The solution is to regularly review all your old 401(k) accounts and consider rolling them into a low-cost IRA if your new employer’s plan has high fees or limited options.
The Industry Shift Toward Low-Cost Defaults and What It Means
The good news is that the industry trend is unmistakably moving toward lower-cost 401(k) defaults. Target-date fund fees have dropped from 0.87% in 2004 to 0.36% by 2023, a 59% reduction in the average fee. Many Fortune 500 companies have switched to low-cost index funds as their default investments, pressuring record keepers and plan sponsors to compete on cost. New regulations and increased scrutiny from the Department of Labor have made plan sponsors more accountable for the fees they charge.
If your employer is considering a plan redesign, or if you’re negotiating benefits at a new job, you now have data to push for low-cost defaults. Average 401(k) balances grew 11% in 2025, reaching $146,100, according to Fidelity’s analysis of 25 million accounts. Workers with access to low-cost plans are capturing that growth more efficiently than those in expensive plans. As the regulatory and competitive environment continues to shift, older, expensive plans will become increasingly indefensible, and employers will have to act.