7 costly 401(k) rollover mistakes to avoid
Rollovers are simple — until a small misstep triggers taxes, penalties, or years of higher fees. Here are the seven that cost people the most.
A 401(k) rollover should be a non-event: the money moves from one account to another and the IRS never gets a cut. But a handful of avoidable missteps turn that simple transfer into a five-figure — sometimes six-figure — mistake. This guide walks through the seven errors that cost people the most, shows the real dollar math behind them, and gives you a clean checklist for doing it right.
Illustrative for someone under 59½. A direct (trustee-to-trustee) rollover moves the full balance with no tax. Cashing out means 20% is withheld toward your tax bill up front (a prepayment, not an extra tax), the full amount is taxed as ordinary income, and a 10% early-withdrawal penalty applies.
How a 401(k) rollover actually works
A rollover moves money from a former employer's 401(k) into another tax-advantaged account — usually an IRA, sometimes a new employer's plan — without triggering tax. There are two ways to do it, and the difference is where most damage happens.
A direct rollover (also called trustee-to-trustee) sends the money straight to the receiving custodian. No tax is withheld, no clock starts, and no tax is due — you get a Form 1099-R coded as a rollover and report the amount on your return as a nontaxable rollover. An indirect rollover pays the money to you first; you then have 60 days to redeposit it. The IRS explains both paths in its rollover guidance, and the takeaway is simple: almost everyone should choose the direct route.
1. Cashing out instead of rolling over
This is the single most expensive mistake, and it is shockingly common when people change jobs. Take the cash instead of rolling it and the plan must withhold 20% for federal tax up front — a prepayment toward your final bill, not an extra tax — the full amount is taxed as ordinary income, you owe a 10% early-withdrawal penalty if you are under 59½, and — the part that hurts most — you surrender decades of compounding.
The lifetime cost dwarfs the upfront hit. A modest balance left to grow can become the difference between a comfortable retirement and a tight one.
The real cost of a cash-out
Say you cash out a $50,000 balance at age 35 in the 22% federal bracket. Here is the immediate damage and the long-term opportunity cost, assuming a 7% average annual return over 30 years:
| Item | Amount |
|---|---|
| Balance cashed out | $50,000 |
| Federal income tax (22%) | −$11,000 |
| Early-withdrawal penalty (10%) | −$5,000 |
| Cash actually in your pocket (before state tax) | ≈ $34,000 |
| What $50,000 could have grown to in 30 years at 7% | ≈ $380,000 |
So a $50,000 cash-out costs roughly $16,000 in immediate tax and penalty and forfeits a future balance near $380,000. Rolling it over instead preserves every dollar to keep compounding.
2. Doing an indirect rollover by accident
If the check comes to you, the 60-day clock starts immediately — and there is a hidden trap. Your old plan must withhold 20% for federal taxes on an indirect rollover, but to avoid tax you have to redeposit the full original amount, including the 20% you never received. You make up that gap out of pocket and recover it as a refund later.
3. Missing the 60-day window
On an indirect rollover, day 61 is a cliff. The IRS treats the money as a distribution — fully taxable, plus the 10% penalty if you are under 59½ — and reversing that after the deadline is difficult and never guaranteed.
There are narrow escapes: a self-certification procedure for qualifying reasons like a misplaced check, serious illness, or financial-institution error, and case-by-case private letter rulings. But these are fallbacks, not a plan. The only reliable way to never miss the window is to never start the clock — choose a direct rollover and there is no deadline at all.
4. Rolling into a higher-fee account
A rollover is only a win if the destination is at least as cheap as the account you left. Some IRAs, "rollover specials," and annuity products carry sales loads, surrender charges, or expensive actively managed funds that quietly erode returns for years. A seemingly small fee gap compounds into real money.
What a 1% fee difference does over time
Consider a $200,000 rollover growing for 25 years at a 7% gross return, comparing a low-cost option at 0.10% in annual fees against a high-cost one at 1.10%:
| Scenario | Net return after fees | Balance in 25 years |
|---|---|---|
| Low-cost account (0.10% fee) | 6.90% | ≈ $1,060,000 |
| High-cost account (1.10% fee) | 5.90% | ≈ $838,000 |
| Difference | 1.00% | ≈ $222,000 |
5. Triggering an accidental Roth conversion
Account types matter. Rolling a traditional 401(k) into a Roth IRA is a Roth conversion — a fully taxable event in the year you do it, because pretax money becomes after-tax money. People who tick the wrong box on a transfer form can land a surprise tax bill on the entire balance.
Match account types unless you are deliberately converting: traditional to traditional IRA, and Roth 401(k) to Roth IRA. If you do want a conversion — which can be smart in a low-income year — plan for the tax in advance and consider paying it from outside funds rather than from the rolled-over money. The IRS covers the mechanics in its rollover rules page.
6. Forgetting after-tax basis or company stock
Two special situations can save — or cost — serious money if you roll on autopilot.
First, after-tax contributions. If your 401(k) holds after-tax (non-Roth) money, you may be able to direct that portion to a Roth IRA tax-free while the pretax portion goes to a traditional IRA. Roll it all into one traditional IRA and you can muddy your basis for years.
Second, net unrealized appreciation (NUA). If your plan holds highly appreciated employer stock, NUA lets you pay ordinary income tax only on the stock's original cost basis and long-term capital-gains rates on the appreciation — often a large savings. Rolling that stock into an IRA forfeits NUA permanently. Because the rules are unforgiving and one-shot, a tax professional should weigh in before you touch employer stock.
7. Leaving the money sitting in cash
This one feels minor and costs more than people expect. Rolled-over funds almost always land as cash or a default money-market sweep in the new account, and they sit there uninvested until you place trades. Nothing is automatic.
It is easy to assume the rollover "is done" once the balance appears, then leave it idle for months while the market moves without you. Reinvest according to your target allocation the moment the money arrives, and double-check a few weeks later that the trades actually settled.
Who should roll over — and who should wait
A rollover is a decision, not a default. Weigh your situation before moving anything.
Rolling to an IRA tends to make sense if you want broader, cheaper investment options, prefer to consolidate scattered old accounts, or are leaving a plan with high fees and limited fund choices.
Leaving it in a 401(k) — old or new — can be better if you have a low-cost institutional plan, value the stronger creditor protection that workplace plans generally carry, separated from service in the year you turn 55 or later (the "rule of 55" lets you tap that plan penalty-free), or plan a backdoor Roth and want to avoid the pro-rata rule that a large traditional IRA balance can trigger.
| Factor | Roll to IRA | Keep in 401(k) |
|---|---|---|
| Investment choices | Very broad | Limited to plan menu |
| Typical fees | Can be very low | Varies — often low at large employers |
| Creditor protection | Good (varies by state) | Strong federal protection |
| Penalty-free access at 55 | No | Yes, if you left that job |
| Backdoor Roth friendliness | Can complicate it | Keeps IRA balance at zero |
How to do it right: a clean checklist
Most rollovers go smoothly if you follow the same disciplined steps each time.
- Open the receiving account first so the money has somewhere to land — a traditional IRA for pretax 401(k) money, a Roth IRA for Roth 401(k) money.
- Request a direct rollover from your old plan, with the check or wire payable to the new custodian "for the benefit of" you.
- Confirm the account types match to avoid an accidental Roth conversion, and flag any after-tax basis or employer stock for special handling. If you've reached RMD age (73, or 75 if born 1960 or later), take that year's required minimum distribution before you roll — RMDs can't be rolled over.
- Compare fees — the all-in expense ratio and any surrender charges — against your old plan before you commit.
- Invest the cash as soon as it arrives, then verify the trades settled.
- Keep the paperwork, especially the 1099-R coded as a rollover, for your tax records.
Done carefully, a rollover preserves every dollar and your tax-deferred status. Done carelessly, it is one of the most expensive paperwork errors in personal finance — so slow down on the steps above.
Related: how to roll over a 401(k) and traditional vs. Roth IRA.
