What to do with an old 401k depends on finding it first. The account is often still with a former employer's plan. Until you know that, the four common choices (leave it, roll it to an IRA, move it to a new job's plan, or cash it out) are guesses.
We make Asset Recovery: Lost 401k, a free app that opens official search tools from the employer name and the years you worked. The decision comes after that search. This page is general education, not financial advice, and it does not promise you will find a balance.
Leave it in the old plan, if the plan allows a small former employee to stay.
Roll it to an IRA so the money sits in an account you control.
Roll it into a new employer's plan, if that plan accepts incoming rollovers.
Cash it out, which can trigger taxes and, if you are under 59 1/2, an extra penalty.
You can only pick among real options after the plan administrator confirms the account. Start with how to find a lost 401(k) from a previous job. You do not need the account number to begin. The search without an account number uses the company name, work years, and an old W-2.
Leaving the money where it is can be reasonable when fees are low, the investments still fit, and you can keep getting statements. A forgotten plan is a weak version of "leave it." You may be paying fees you never review, and a small balance can be forced out under the plan's rules (a check, or a move into a default IRA) even if you do nothing.
If the company closed, merged, or changed names, "leave it" still requires you to know who the administrator is now. That situation is covered in 401(k) when a company closes, merges, or is renamed.
A rollover moves the balance to an IRA or to a new job's plan without treating it as a withdrawal, when it is done as a direct rollover. An IRA is a common next step when you want one place for several old jobs. A new employer's plan is a common next step when that plan accepts rollovers and you prefer to keep workplace money together.
Either path needs the current plan administrator. Lost 401k gets you to the official search so you can find that contact. It does not fill out rollover paperwork for you. After you locate the account, some people look at an IRA rollover. Empower is one option people compare. Open Lost 401k and use the partner card in the app if you want to look at it. You can use Lost 401k without it.
Cashing out means the plan pays you. Taxes often apply. An early withdrawal penalty can apply if you are under 59 1/2. A force-out of a small balance is different from a cash-out you request, but the check can still be taxable. Miss the check and the leftover can later show up as state unclaimed property, which is a different search from the 401(k) databases listed in free places to look.
Asset Recovery: Lost 401k is the locate step. You enter each former employer. The app opens DOL Lost and Found, Abandoned Plan Search, or PBGC, depending on the situation. Your Social Security number, if a government site needs it, stays on that site.
Once you know where the account is, you choose leave, roll, or cash out with the administrator and, if you want, a tax or financial professional. Comparing apps before you search is fine. See apps to find a lost 401k. Then do the employer list in Lost 401k so the "what now" question has a real account behind it.
Start on our Asset Recovery page or download Lost 401k.