I'm 45 and I just found out about a 20-year-old 401(k) account with $25,000 in it. Where should I put the money?

You can track down these assets using services like the U.S. Department of Labor’s Retirement Savings Lost and Found Database or by contacting former employers. But say you do track down an abandoned account: What’s the next step?

Let’s imagine, for example, that Juan, 45, worked at a car dealership in his 20s and contributed money to his 401(k). He left the job at 25, completely forgot about it, and recently received a letter from the plan administrator warning that the company will start charging a monthly non-employee maintenance fee if he doesn’t transfer the account.

Now, thanks to appreciation, Juan has $25,000. He has to decide what to do with the money. What are his options?

Here are a few potential things he can do.

Leave the money where it is

Juan can choose to leave the money where it is if he wants to. But this usually would be a bad idea, since he’s been warned he’ll now owe fees.

Research from PensionBee revealed that the monthly maintenance fees you often pay when you abandon an old 401(k) account can add up dramatically because of lost compounded investment returns.

In fact, according to their analysis, if you work for 33 years, change jobs every three years, earn 5% returns minus average 401(k) fees, and the fees for keeping the old account total just $4.55 per month, the long-term costs of those added fees can total almost $18,000 over time, including lost compounding.

There’s no reason for Juan to lose money to an extra administration fee every single month when there are other, better solutions.

Merge the plan into a new employer’s 401(k)

Juan’s next option is to roll the money into his new employer’s 401(k).

This can be a convenient solution if he’s already contributing to his current employer’s plan. Juan could avoid managing multiple accounts and keep all of his retirement dollars with his new employer, so he can easily see his overall asset allocation and future retirement income projections.

Unfortunately, many 401(k) accounts do have limited investment options compared to other types of retirement plans. The investments may have higher fees, and there may also be administration costs associated with the new plan.

Plus, if Juan leaves his current employer, he’s going to have to move all this money somewhere else, or risk forgetting about it again.

Rolling the money into an IRA

Rolling the money into an IRA is another alternative, and can be a good option.

Juan can open a traditional IRA with nearly any brokerage firm, and moving a traditional 401(k) into a traditional IRA shouldn’t have any tax consequences.