What to Do With an Old 401(k): Four Options, Honest Math

You have four things you can do with a 401(k) left behind at an old employer: leave it where it is, move it into your new employer’s plan, roll it into an individual retirement account, or cash it out. Three of those are reasonable. The fourth, cashing out, is the one most people reach for and the one that costs the most, because a distribution before age 59 and a half is taxed as ordinary income and then hit with an extra 10 percent additional tax on top, per the Internal Revenue Service rules on early distributions.

The honest answer to which of the other three is right is not universal. It turns on four things: the fees inside each plan, whether you want the option to do a backdoor Roth contribution later, whether you might retire between 55 and 59 and a half, and whether you are at any real risk of being sued. This article works through each of those with numbers attached.

First, find out whether the money is still there

A surprising amount of 401(k) money is not where its owner left it. Under federal rules described by the Department of Labor’s Employee Benefits Security Administration, when a worker leaves a job with a vested balance of 7,000 dollars or less, the plan can automatically roll that balance into a safe harbor individual retirement account without the worker’s consent, provided the plan document allows it and the worker does not respond to the required notices. That threshold rose to 7,000 dollars under Section 304 of the SECURE 2.0 Act of 2022.

This matters because safe harbor IRAs set up by a former employer are typically invested conservatively, in a money market or stable value option, to protect the balance rather than grow it. Money parked there can sit for years earning very little while its owner assumes it is still invested in whatever fund they originally chose.

Two things to check before you plan anything:

• Log in to the old plan’s recordkeeper. If the balance is gone, the plan sent it somewhere, and the notice went to whatever address they had on file.
• Search the Retirement Savings Lost and Found Database, which the Department of Labor launched in December 2024 under Section 303 of the SECURE 2.0 Act. It is a free federal search tool for exactly this problem.

The Department of Labor reported in January 2024 that defined contribution plans covered an estimated 86.6 million participants holding 9.3 trillion dollars in assets. At that scale, a great deal of money goes quietly astray.

Option one: leave it in the old plan

Leaving it alone is the default, and it is not always the lazy answer. Large employer plans often have institutional share classes with expense ratios no retail investor can buy on their own, and plan-level administrative costs that a big participant base spreads thin.

Leaving it works when the old plan is cheap and the fund lineup is decent. It stops working when the plan is small, expensive, or charges separated participants a flat annual account fee that the employer used to absorb. That last one is common and easy to miss. Read the annual fee disclosure the plan is required to send you, and look specifically for a per-account charge now billed to you rather than the company.

You also cannot contribute to it any more, you may face restrictions on partial withdrawals in retirement, and if you repeat this at four more jobs you end up with five accounts and no coherent allocation across them.

One real advantage worth knowing about

If you separate from service during or after the calendar year in which you turn 55, the Internal Revenue Service allows you to take distributions from that employer’s qualified plan without the 10 percent additional tax on early distributions. The IRS exception chart is explicit that this exception applies to qualified plans such as 401(k)s and does not apply to IRAs. For certain public safety employees the age is 50.

So if you might stop working in your mid to late fifties and expect to need this money before 59 and a half, rolling it into an IRA destroys that option permanently. That is the single most expensive mistake in this whole decision, and almost nobody mentions it.

Option two: roll it into your new employer’s plan

This is the tidiest outcome when the new plan is good. One account, one allocation, contributions continuing, and the age 55 separation exception preserved because the money is still in a qualified plan.

It has a second benefit that only matters to higher earners. Money inside a 401(k) is invisible to the pro-rata rule that governs IRA conversions. If you ever want to make a non-deductible traditional IRA contribution and convert it to Roth, the taxable share of that conversion is calculated across all of your traditional, SEP and SIMPLE IRA balances combined. A large pre-tax rollover IRA makes that conversion mostly taxable and effectively closes the strategy. Keeping the old balance in a 401(k) instead of an IRA keeps the door open.

The constraint is that the new plan has to accept incoming rollovers. Many do; some do not. Ask the plan administrator directly rather than assuming.

Option three: roll it into an IRA

An IRA gives you the whole investable universe instead of a menu of twenty funds, and it is usually cheaper if the old plan was expensive. You can also convert some or all of it to Roth, though converting pre-tax money means paying ordinary income tax on the converted amount in the year you convert it. If the choice between Roth and traditional treatment is not already settled in your head, settle it before you convert anything rather than after.

The costs are the mirror image of the benefits above. You lose the age 55 exception. You complicate any future backdoor Roth contribution. And you move from a plan governed by the Employee Retirement Income Security Act, whose anti-alienation protections are strong, to an account whose protection in bankruptcy is capped at an inflation-adjusted dollar limit under the federal Bankruptcy Code as amended by the Bankruptcy Abuse Prevention and Consumer Protection Act of 2005, with amounts traceable to an employer plan rollover excluded from that cap. Protection from non-bankruptcy creditors varies by state.

Do it as a direct rollover, and be exact about the wording

There are two ways to move the money and only one of them is safe.

A direct rollover sends the money from the old plan straight to the new plan or IRA. The IRS states that mandatory withholding does not apply to direct rollovers or to checks made payable to the receiving plan.

An indirect rollover sends the money to you first. The IRS is blunt about what happens then: a retirement plan distribution paid to you is subject to mandatory withholding of 20 percent, even if you intend to roll it over later. You then have 60 days from the date you receive it to get it into the new account, and you have to replace that withheld 20 percent out of your own pocket to roll over the full amount. If you do not, the shortfall is treated as a taxable distribution, with the 10 percent additional tax on top if you are under 59 and a half.

Here is what that looks like on a 48,000 dollar balance, using the IRS withholding and penalty rules as the only inputs.

The withheld 20 percent is not lost in the middle column; it comes back as a credit when you file. But you have to front it, and you have 60 days. The simplest protection is never to let the money touch your own account. Ask for a direct trustee-to-trustee transfer and have the check made payable to the receiving institution for your benefit, not to you.

One more trap: the IRS limits you to one IRA-to-IRA rollover in any 12-month period, aggregated across all your IRAs, for rollovers made after January 1, 2015. That limit does not apply to trustee-to-trustee transfers, to plan-to-IRA rollovers, to IRA-to-plan rollovers, or to Roth conversions. Another reason to use transfers rather than rollovers wherever the choice exists.

Option four: cash it out, and what it actually costs

Cashing out is taxed as ordinary income, plus the 10 percent additional tax under 59 and a half with limited exceptions. That is the visible cost. The invisible cost is the compounding you gave up, and it is far larger.

Say the balance is 48,000 dollars and you are 32, with 35 years until you stop working. Cash it out and you keep perhaps 30,000 dollars after federal tax at a middling bracket, the 10 percent additional tax and state income tax. Leave it invested and, at a 7 percent average annual return, 48,000 dollars becomes roughly 512,000 dollars in 35 years. The question is not whether 48,000 dollars is worth having now. It is whether it is worth half a million dollars later.

The fee question, with the Department of Labor’s own arithmetic

Fees are the one input in this decision you can actually measure, and they dominate over long horizons.

The Department of Labor publication “A Look at 401(k) Plan Fees” works a specific example. A participant with 35 years to retirement, a 25,000 dollar balance, no further contributions and a 7 percent average annual return finishes with 227,000 dollars if fees and expenses run 0.5 percent a year. At 1.5 percent a year, the same participant finishes with 163,000 dollars. The publication states plainly that the 1 percent difference in fees and expenses would reduce the account balance at retirement by 28 percent.

That is the number to carry into this decision. Not a rounding error. More than a quarter of the ending balance, for a difference you can read off a fee disclosure in five minutes.

So the practical exercise is this. Find the all-in annual cost of the old plan, the new plan and the IRA you would open. All-in means the weighted average expense ratio of the funds you would actually hold, plus any plan administrative fee charged to your account, plus any IRA custodian fee. Then compare. If you are opening the IRA from scratch, the decision between a robo advisor and a do-it-yourself index portfolio is mostly a decision about this same number.

Those figures are straightforward compound growth arithmetic on a single balance with no further contributions, at 7 percent gross less the stated annual cost. They are illustrative, not a forecast. The point is the shape: a one percentage point fee difference on a mid-sized balance is worth tens of thousands of dollars over a working life, which is why the fee comparison should drive this decision more than branding or convenience.

A decision rule you can actually apply

Work through these in order and stop at the first one that fits.

1. If you expect to leave the workforce between 55 and 59 and a half and may need this money then, leave it in the old 401(k) or move it to your new employer’s plan. The age 55 separation exception is worth more than a small fee saving, and an IRA cannot give it back to you.
2. If your income is high enough that you use or may use backdoor Roth contributions, move it to the new employer’s plan rather than an IRA. Pre-tax money sitting in an IRA makes those conversions largely taxable through the pro-rata rule.
3. If the old plan’s all-in cost is within about 0.15 percentage points of your alternatives and the fund lineup is fine, leave it alone. The paperwork is not worth it, and a rollover done carelessly is how people end up with an accidental taxable distribution.
4. If the old plan is expensive, charges separated participants an account fee, or has a weak lineup, roll it. To the new employer’s plan if that plan is good and accepts rollovers; to an IRA if it is not.
5. If the balance is under 7,000 dollars, deal with it now rather than later. The plan is permitted to move it into a conservative safe harbor IRA without your agreement, and that is the version of this decision made for you, badly.
6. Cash out only if the alternative is genuine hardship you have no other way to cover. Not for a car, not to pay off a low-rate loan, not because the balance feels too small to bother with.

Whatever you choose, request a direct trustee-to-trustee transfer, confirm in writing where the check is going and to whom it is payable, and check that the money arrived and got invested. Rollover money frequently lands in cash and stays there, because the receiving institution has no instruction about what to buy. A rollover you completed but never invested is a rollover that cost you the market’s return for however long it sat.

What this decision cannot fix

None of these four options changes how much is in the account. Fee optimisation on an old balance is worth real money, but it is second-order next to the contribution rate going forward, and it is worth being clear-eyed about that. If the old 401(k) holds 20,000 dollars and you are contributing nothing to the current one, the rollover question is the smaller problem on your desk. Capturing the full employer match at your current job, and funding an HSA if you are eligible for one, both move the needle further than anything in this article.

The reason it still deserves an afternoon is that it is a decision with a deadline attached that nobody tells you about. Plans force out small balances. Addresses go stale. Recordkeepers change and logins break. The old account does not get better by being ignored, and the version of this choice that happens by default is reliably worse than the one you make on purpose.

Where these figures come from

• Internal Revenue Service, Rollovers of retirement plan and IRA distributions
• Internal Revenue Service, Retirement topics, Exceptions to tax on early distributions
• U.S. Department of Labor, Employee Benefits Security Administration, A Look at 401(k) Plan Fees
• U.S. Department of Labor, Employee Benefits Security Administration, news release on automatic portability transactions, January 2024
• SECURE 2.0 Act of 2022, Sections 303 and 304
• Bankruptcy Abuse Prevention and Consumer Protection Act of 2005

General information, current as of October 2026, and not personalised financial advice. Contribution limits, thresholds and tax rules change; check the primary sources before acting on anything with money attached.