What's actually in your old 401(k), and what it costs

Published 2026-10-02

If you have changed jobs a few times, there is a good chance a 401(k) from an earlier employer is still sitting where you left it. It may be the account you log into least and understand least. It is also often the one with the fewest investment choices, which makes it easy to check once you can see the list.

This page covers three things: how to find the account, how to get the list of funds in it and what each one charges, and how to turn that into a dollar figure you can compare with your other accounts. It does not tell you what to do with the account. That is a separate decision with tax and plan-specific consequences, and it belongs with a tax professional or the plan itself.

Step 1: Find the account

Start with whichever of these you can do today.

Old statements and mail. Look for a plan statement or a letter from a retirement plan recordkeeper. The recordkeeper's name (a large brokerage or insurer is common) is more useful than the employer's.
Old paperwork. A year-end pay stub, or the benefits section of an old offer letter or HR portal, usually names the plan and the provider.
Your former employer's HR or benefits team. Ask which company administers the plan. They can usually tell you in one email.
The Department of Labor's Retirement Savings Lost and Found database, at lostandfound.dol.gov. It helps you search for retirement plans that may still owe you benefits. You need to have worked for a private-sector employer or union that sponsored the plan, and you sign in with a Login.gov account that has been identity-verified. It covers pension and 401(k)-type plans from private-sector employers and unions. It does not cover IRAs, government plans or certain religious-organization plans. Its records are historical and may be out of date, so a result shows you took part in a plan at some point, not that money is still there. Only the plan administrator can confirm what is owed.
The plan's annual filing. Most private-sector plans file a Form 5500, and the filings are searchable by the public at efast.dol.gov. It will not show your balance, but it names the plan and its administrator.

Once you have the provider, you can usually register for online access with the plan name, your Social Security number and some personal details, or by calling the number on the provider's site.

Step 2: Get the fund list and each fund's expense ratio

Then find each fund's expense ratio, the percentage of the money in the fund that is deducted each year to run it. A 0.50% expense ratio means $5 per year for every $1,000 in that fund.

Where to look:

The plan's annual fee disclosure. Plan administrators are required to give participants a disclosure that lists each investment option's expense ratio. The rule is 29 CFR 2550.404a-5, and the expense ratio must be furnished at least once every 14 months. If you cannot find it in the online portal, ask the plan administrator for it.
The fund's own page and prospectus. Look for "Total annual fund operating expenses". Funds offered only inside retirement plans may not have a public page, in which case the plan disclosure is the source.

If the plan holds a target-date fund, its expense ratio is the single figure for the whole fund. The fund itself is made up of other funds, which matters in step 3.

Step 3: Turn it into dollars per year

Multiply each balance by its expense ratio, then add them up. If your balances are not equal, do not average the percentages. Weight them by the dollars in each fund. The full method is in what your funds actually cost you per year.

A worked example (hypothetical)

These funds and figures are made up to show the arithmetic. They are not real funds and not typical of any plan.

Account	Balance	Expense ratio	Cost per year
Old employer 401(k) — one target-date fund	$60,000	0.65%	$390
IRA — one broad index fund	$90,000	0.05%	$45
Taxable brokerage — one broad index fund	$50,000	0.04%	$20
Total	$200,000	0.23%	$455

The weighted expense ratio is $455 ÷ $200,000 = 0.2275%, about 0.23%. The old 401(k) holds 30% of the money and accounts for about 86% of the annual cost. That kind of gap is easy to miss when each account is viewed on its own statement, and it is the reason to look at the accounts together. It is not a reason to do anything in particular. Plans differ in what they offer, and cost is one factor among several.

Step 4: Check whether the old 401(k) duplicates what you already hold

Funds in different accounts often own many of the same companies. A target-date fund, for example, holds other funds that hold stocks and bonds, and a broad index fund in your IRA may hold many of the same companies.

The fund overlap calculator takes two to five tickers and a portfolio value, shows how much of the underlying holdings those funds share, and returns what their expense ratios cost per year in dollars. It splits the value equally across the funds you enter, so if your balances are very unequal, use the weighted calculation in step 3 for the cost figure. Plan-only funds without a public ticker cannot be entered, so you will need the plan's holdings list for those.

What this page does not cover

Whether to leave the money, move it, or change what is in it. The answer depends on your plan's options and fees, your tax situation, and rules that differ by plan. A tax professional or the plan administrator can answer that.
Returns. An expense ratio is a cost, not a measure of performance.
Taxes. Moving or selling can trigger them.

Datum shows you what you own. It does not give investment advice or recommend what to buy or sell.