(NerdWallet) – Sept. 8, the Friday after Labor Day, marks National 401(k) day. It’s the day Americans are encouraged to check in on their retirement readiness.

But what about all the 401(k)s out in the ether? If you’re not sure where one of your 401(k) accounts is, now is as good a time as any to find it.

According to Capitalize, a company that helps consumers find and transfer retirement accounts, there were 29.2 million lost 401(k) accounts in May 2023, worth about $1.65 trillion.

Even if you’ve left a small balance behind, it could be valuable when you retire.

What’s so great about 401(k)s, anyway?

Adrianna Vargo, a certified financial planner at Domain Money in Cleveland, Ohio, sees a myriad of tax benefits with the 401(k) plan. Contributing to a pre-tax traditional 401(k) reduces your taxable income, while a Roth 401(k) allows you to contribute after-tax money but enjoy tax-free growth and tax-free withdrawals.

Another key advantage of the 401(k) is the employer match, if it’s offered. If you put a certain percentage of your paycheck into a 401(k), let’s say 3%, some companies will match that percentage. “You essentially get free money just for contributing,” Vargo says.

And whether you leave your job, you get laid off, or you’re fired, that 401(k) money is yours to keep.

Why look for a lost 401(k)?

“I think it’s worth the effort for several reasons,” Vargo says. “The first one being so that you don’t lose track of it long term. And if it goes too long without having your eyes on it, you may completely forget about it. And we don’t want to lose out on that money.”

She also says that investment options and strategy change over time, depending on your money goals and how close you are to retirement. Keeping all your accounts in one place gives you an overview of how it’s invested and where it stands.

When you leave your job, you have four options with your 401(k), each one with its own pros and cons, says Thao Truong, a CFP with Morton Wealth in Calabasas, California.

Cashing out is one option, but that would mean paying taxes and early withdrawal penalties. Or you could roll it over to your new employer’s retirement plan. Another option is to roll it over into an individual retirement account (IRA). The last option would be to leave the account at your current company.

“You don’t have to make any decisions,” Truong says, “but the problem is that you can easily forget about it.”

How do I find my lost 401(k)?

Contact your previous employer

If you think you have a 401(k) from a previous job, finding it could take some effort. Start with the human resources department of your last employer. The department should be able to connect you with the plan administrator or tell you if the account has been transferred to a new provider.

If you have an old statement, you can skip this step and contact the plan administrator directly.

Search databases

You can use your Social Security number to search for old retirement plans in various databases, either by yourself or with the help of a financial advisor.

Try government websites, such as the Department of Labor’s Abandoned Plan Search and the U.S. Pension Guaranty Corp. for unclaimed pensions.

You could also use databases such as the National Registry of Unclaimed Retirement Benefits, the National Association of Unclaimed Property Administrators site MissingMoney.com, and FreeErisa, an employee benefits database. These databases compile information on lost retirement accounts and are publicly accessible.

Other websites, such as Capitalize, also allow you to search retirement accounts for free but charge for premium services such as certain rollovers and account management.

I’ve found my 401(k). Now what?

Once you’ve found your 401(k) account, the options are the same as when you leave an employer, Vargo says. Cash it out, roll it over or leave it where it is. Do what’s right for you, she says, but rolling over has its benefits.

“Keeping it all in one house and … knowing what it’s invested in and where it stands is really important.”

If you choose to roll your old 401(k) over to a new one or into an IRA, it does not count toward your annual contribution limit.

You can contribute up to $22,500 to a 401(k) in 2023 as an individual, and an additional $7,500 as a catch-up contribution if you’re 50 or older. For IRAs, you can contribute up to $6,500 per year ($7,500 if you’re 50 or older).

After you make your plans, you have a good opportunity to review your retirement accounts. Vargo recommends doing this periodically throughout the year, especially when you know what your income was for the prior year and what you think it might be in the next year.

“With the caveat, though, if you do have a big change in income or a change in your family dynamic, maybe you had a baby or something along those lines, those life-change events are always a good time to review, too, and make sure that where you’re saving your money each month aligns with your long-term and short-term goals.”

Then, for the most part, try not to think about it, Vargo says.

Truong also says you don’t need to check your fattened-up 401(k) account daily.

“You’re investing for the future, not tomorrow,” she says. “The more you look at it, the easier you get emotionally attached to market movement, and market movement happens every day. If you get emotional … you’re going to buy and sell.”

Instead, she recommends reviewing your plan once per quarter, or once a year, to make sure your plan is growing according to your goals.

The perfect time each year to check in? Maybe the Friday after Labor Day.