Americans are leaving billions of dollars behind in forgotten retirement accounts, according to a new report.

The Sept. 2025 report by Capitalize, a fintech firm that specializes in helping U.S. workers locate and roll over old 401(k)s, found that the average balance in a forgotten account increased to $66,691 from $56,616 in May 2023.

According to the report, 31.9 million accounts have been left behind holding about $2.1 trillion in assets, up nearly 30% from mid-2023.

The analysis emphasizes that 401(k)s make up a large portion of workers’ retirement savings efforts. As of 2024, around 72% of U.S. workers in the private sector have access to retirement plans like a 401(k) and 53% participate in them.

Experts say the growing number of lost 401(k) accounts has almost doubled over the last decade due to workers switching jobs and layoffs.

When you switch jobs, there are options for handling your old 401(k). You could roll over the money, move it into an individual retirement account (IRA) or cash it out.

Another option is to leave the money with your former employer. The Capitalize report focuses on this group of Americans who postpone their decision and leave it for later. However, the end result is a series of 401(k) accounts left behind and forgotten.

Left behind 401(k)s come with a risk

When you leave your 401(k) behind with a former employer, the money doesn’t disappear, but it remains invested and subject to market fluctuations and fees.

A 2021 study by the U.S. Government Accountability Office found that 41% of these retirement account participants do not know they pay fees. This lack of awareness means many workers are losing money without realizing it.

According to the report, fees pile up on forgotten 401(k) accounts without regular contributions and could end up costing over $500,000 in savings in the span of an individual’s career. The median 401(k) fee is about 0.75% of assets per year.

Over time, monitoring and rebalancing a portfolio becomes more difficult and easy to forget for an account holder. A former employer may do a “forced rollover.” This transfers inactive accounts into low-interest holding accounts.

For most workers, leaving a 401(k) account behind can translate into missed savings opportunities and unnecessary fees over a lifetime.

How to find a forgotten 401(k)

Start by contacting your previous employer’s human resources department. They can tell you who administers the company’s 401(k) plan and how to access your account.

If you cannot get in touch with the employer or if the company no longer exists, you can search for your retirement plan using the following online databases:

Retirement Savings Lost and Found DatabaseNational Registry of Unclaimed Retirement Benefits

Your Social Security number, employer name and the dates you worked for your previous employer may be needed to complete the search.

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