Rollover IRA vs leaving it in the old 401(k)
Last updated August 2026
Short answer
The industry has an interest in this decision, since a rollover moves assets to a firm that charges for holding them. That is a reason to check the reasoning rather than to accept the default.
What the IRA gives you
Any investment the custodian offers, rather than a menu somebody else chose.
Consolidation, so one account replaces several from previous jobs.
Simpler required distributions later, since IRA balances are aggregated and the total can come from any one of them.
What the old plan may give you
Institutional share classes that can be cheaper than anything available retail, particularly in large employer plans.
The rule of 55, if you separated in or after the year you turned 55, which no IRA offers.
Broad creditor protection under ERISA, which matters for anyone with professional liability exposure.
The backdoor Roth consideration
A conversion draws proportionally from all pre-tax IRA balances, so a large rollover IRA makes the backdoor route expensive.
Money left in a 401(k), or rolled into a new employer's plan, is excluded from that calculation entirely.
For a high earner who contributes through the backdoor each year, this single point frequently decides the whole question.
Try it in Walnut
Walnut connects to your brokerage and reads a rollover IRA alongside everything else, which is the view that shows whether consolidating actually simplified anything.
Comparing the costs honestly
Find the plan's fee disclosure, which lists fund expense ratios and any administrative charge.
Compare that against what the same exposure costs in an IRA, including any account fee the custodian charges.
Small plans frequently lose this comparison, and large ones frequently win it, which is why the answer is plan-specific rather than general.
Doing it correctly if you do move
Use a direct rollover, trustee to trustee, so nothing is withheld and nothing has to be replaced.
Taking the money personally triggers 20% mandatory withholding, and you must make up that amount from your own funds within 60 days to avoid tax on it.
Keep pre-tax and Roth balances separate through the move, and confirm the receiving account is correctly designated before the transfer is initiated.
Company stock and net unrealised appreciation
If the old plan holds employer stock, rolling everything to an IRA can forfeit a valuable treatment.
Net unrealised appreciation rules allow the growth on that stock to be taxed at long-term capital gains rates rather than as ordinary income, if the distribution is handled correctly.
It is a one-time decision with real money attached, and it is worth professional advice before any rollover is initiated.
Sources
Rollover rules, the 60-day window and mandatory withholding are covered by the IRS at Rollovers of retirement plan and IRA distributions, with the exceptions to the additional tax at Exceptions to tax on early distributions and required distribution rules in the RMD FAQs. Walnut is informational and is not an investment adviser. This guide is educational and not personalized tax advice.
FAQ
Should I roll my old 401(k) into an IRA?
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Not automatically. An IRA offers more investment choice and simpler required distributions. The old plan may offer cheaper institutional funds, penalty-free access at 55, stronger creditor protection and a clean backdoor Roth. Compare before moving.
What is the rule of 55?
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Separating from service in or after the year you turn 55 allows penalty-free withdrawals from that employer's plan. Rolling to an IRA destroys it, because IRAs apply the age 59.5 rule with no equivalent exception.
How does this affect a backdoor Roth?
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Considerably. Pre-tax IRA balances trigger the pro-rata rule on conversions, so a large rollover IRA makes a backdoor Roth expensive. Leaving the money in the 401(k), or rolling it into a new employer's plan, keeps the path clear.
Which has better creditor protection?
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Usually the 401(k), which under ERISA generally receives broad protection. IRA protection is strong in bankruptcy and varies by state outside it, so someone in a profession with liability exposure has a real reason to stay put.
Are the fees lower in one or the other?
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It depends entirely on the specific plan. Large employer plans often access institutional share classes cheaper than retail funds. Small plans frequently carry administrative charges that make an IRA cheaper. Read the fee disclosure rather than assuming.
What about required minimum distributions?
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IRAs can be aggregated, so the total may be taken from any one of them. Workplace plans generally have to be calculated and taken separately, so several old accounts each create their own obligation.
Can I roll it into my new employer's plan instead?
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Usually, if the new plan accepts incoming rollovers. That consolidates without creating a pre-tax IRA balance, which is often the best of both routes for someone who uses the backdoor Roth.
What should I never do?
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Take the distribution personally rather than moving it directly. A non-direct rollover triggers 20% mandatory withholding, and you must replace that withheld amount from your own funds within 60 days or it counts as a taxable distribution.
What if my old plan holds company stock?
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Then get advice before rolling anything. Net unrealised appreciation rules can allow the growth on employer stock to be taxed at long-term capital gains rates rather than as ordinary income, and rolling it into an IRA generally forfeits that treatment permanently.
Is there a deadline for deciding?
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Not usually. Plans can force out small balances, commonly under $7,000 under current rules, but larger balances can generally stay indefinitely. That means the decision can wait until you have compared the fees properly.