The 401k Rollover Mistake That Triggers A Tax Bill

A rollover is supposed to be a non event. Money leaves one retirement account, arrives in another, nothing is taxed, nobody notices.

There is one version of it that works exactly like that. There is another version, offered with the same friendliness on the same phone call, that can cost you thousands if you handle it the way it is described to you.

The difference is who the cheque is written to.

Direct: the cheque is never yours

In a direct rollover, also called a trustee to trustee transfer, the old plan sends the money to the new custodian. If a paper cheque is involved at all, it is made payable to the new institution for the benefit of your name, and you are just the courier.

Nothing is withheld. No deadline applies to you. There is no limit on how many you can do.

The money is never legally in your hands, so the tax system never treats it as having been distributed. That is the entire trick, and it is why this is the only version I would recommend to anybody.

Indirect: the cheque is yours, and so is the clock

In an indirect rollover the old plan sends the money to you. You then have 60 days to deposit it into another retirement account, and if you do, the whole thing is still tax free.

Two problems arrive with that cheque.

The first is withholding. When a 401k pays a distribution to you directly, the plan is generally required to hold back 20% for federal tax. On $50,000 that means $10,000 goes to the tax authorities and $40,000 comes to you.

The second is the arithmetic that follows. To complete the rollover you must deposit $50,000, not $40,000, because the rollover is measured against the gross amount. So you need to find $10,000 from somewhere else within 60 days, and you get the withheld $10,000 back as a refund when you file, which may be nine months later.

What it costs if you get it wrong

Say you deposit only the $40,000 you actually received. The other $10,000 is now a distribution, permanently.

You owe income tax on it. On a 22% marginal rate that is $2,200. If you are under the qualifying age, the early withdrawal penalty applies too, 10% as of 2026, which is another $1,000.

$3,200, for a transaction you believed was neutral, on money you never chose to spend.

The $10,000 withholding still comes back to you at tax time. The tax and the penalty do not.

Three more ways to trip

Mismatching the tax treatment

Match the tax treatment on both ends. Pre tax 401k money belongs in a traditional IRA or another pre tax plan. Roth 401k money belongs in a Roth IRA. If you send pre tax money into a Roth, that is not a rollover, it is a conversion, and a conversion is a taxable event by design.

Conversions are sometimes a good idea, and they are never an accident you want to have. $50,000 converted on a 22% rate is $11,000 of tax due for that year, and you should pay it from outside the account rather than out of the converted money, or you have shrunk the balance and possibly triggered the penalty on the part you used to pay the tax.

The once a year rule

There is also a once per twelve month limit on indirect rollovers between IRAs. It does not apply to direct transfers, and it does not apply to a 401k moving into an IRA, but it catches people who treat indirect rollovers as a routine tool. One more reason to never use one.

Why some people roll into the new plan instead of an IRA

An IRA usually gives you a far better menu, because you can hold almost anything instead of the twelve to twenty funds a plan offers. That is the main argument and it is a strong one.

Two arguments run the other way. Workplace plans generally carry strong federal creditor protection, while IRA protection varies by state, which matters more in some professions than others.

The second is narrower and catches people who did not see it coming. If you ever intend to make a non deductible IRA contribution and convert it to Roth, holding a large pre tax IRA balance complicates that, because the tax on a conversion is calculated across all your traditional IRA money proportionally rather than just the amount you converted. Rolling an old 401k into a new 401k keeps that balance out of the calculation. Rolling it into an IRA puts it right in the middle of it.

If that sentence means nothing to you, it probably does not apply. If you recognised it, decide the destination before you start the paperwork, because unwinding it later is harder than choosing correctly now.

The mistake that costs the most and triggers no tax at all

Almost every 401k rollover sells your holdings to cash first. The old plan liquidates, sends money, and the new account receives a cash balance.

Then it sits there.

A rollover does not invest anything. It moves money into an account where the default holding is usually a cash or money market position paying whatever cash pays, and the account will hold it there indefinitely because nobody has told it otherwise. I know of balances that sat as cash for over a year because the person assumed the transfer was the whole job.

There is no penalty for that and no tax. It is just a year of not being invested, which across a long horizon is the most expensive thing in this article.

The phone call, word for word

Call the old plan. Tell them you want a direct trustee to trustee transfer, that the cheque should be payable to the new custodian for the benefit of your name, and that it should not be made payable to you.

Ask two follow ups. Whether any of the balance is after tax or Roth money, because those buckets have to be split correctly. And whether they will send it electronically, which is faster and removes the risk of a cheque with your name on it arriving in your own postbox.

Then put a note in your calendar for three weeks out that says four words: is it actually invested.

That second note is the one that matters.