What Happens To Your 401k When You Quit

The week I left my first job I got a fourteen page packet about my 401k, skimmed the first page, and put it in a drawer.

It stayed there for two years.

Nothing bad happened, as it turns out, which is worth saying up front. Leaving a 401k alone is not a disaster. But there were four doors in that packet and I did not know what any of them cost, and one of them was expensive in a way that is designed not to look expensive.

First, what is already yours

Every dollar you contributed is yours from the moment it left your paycheck. Your last day does not change that, your manager cannot change that, and the company going bankrupt does not change it either, because the assets sit in a trust rather than on the employer's books.

The employer match is the part that can be taken back. Most plans put the match on a vesting schedule, meaning you earn ownership of it over a few years of service, and anything unvested on your last day is forfeited.

That is a resignation date question, not a paperwork question, and it is worth finding out the answer before you give notice rather than after.

The four doors

The one that costs the most

Say the balance is $18,000 and you take it as cash before retirement age.

You owe ordinary income tax on the whole thing. On a 22% marginal rate that is $3,960. On top of that, withdrawals before the qualifying age carry an additional penalty, which in 2026 is 10%, so another $1,800.

$5,760 gone. You keep $12,240 of your $18,000.

There is a second sting in the mechanics. The plan is generally required to withhold 20% for federal tax before it sends you anything, so the cheque is for about $14,400 and the rest shows up as a credit when you file. People budget against the $18,000 and receive $14,400, which is how a cash out turns into a surprise.

And then the part that does not show up on any statement. $18,000 left alone for thirty years at 7% becomes about $137,000. That is $18,000 times 1.07 raised to the power of 30, which you can check in ten seconds.

$137,000.

I am not going to pretend nobody has a good reason. If the alternative is a 25% credit card spiral or missing rent, take the money and do not feel clever or stupid about it. But it should be a decision you made with the $137,000 written down in front of you, not a default you picked because it was the button with the fewest steps.

If you borrowed from it, read this part first

An outstanding 401k loan does not simply travel with you. When you leave, the unpaid balance generally becomes due, and plans give you a window rather than a schedule.

Miss it and the unpaid amount is treated as a distribution. A $12,000 outstanding loan on a 22% rate becomes about $2,640 of income tax plus a $1,200 penalty if you are under the qualifying age, arriving in a year when you may not have a salary.

There is usually a route out, which is repaying the balance or rolling an equivalent amount into an IRA by your tax filing deadline for that year. It is not automatic and nobody chases you about it.

The fifth option nobody lists

You can split it. Roll the pre tax portion into an IRA and leave a small balance behind, or move part to the new plan and part to an IRA, if both administrators will cooperate.

Most people should not bother. But it is worth knowing the four doors are not actually exclusive, because plenty of people believe they have to accept one menu wholesale.

The one that costs the most quietly

Leaving it is free. It is also the option where nothing ever prompts you again.

Three things go wrong slowly. You keep paying the old plan's fees, and you no longer have an employer with any incentive to negotiate them down on your behalf. You cannot change the menu, so if the plan's cheapest option is 0.65% you are stuck with 0.65%, which on $18,000 is $117 a year. And small balances can be handled by the plan without much input from you, because plans are allowed to move out former employees below certain thresholds, sometimes into an IRA chosen for you, sometimes as a cheque.

The failure mode is not dramatic. It is an account you forget about, at an address you moved out of, held by a company whose name you no longer remember.

There is real money sitting in exactly this state across the country, and every dollar of it belongs to somebody who meant to deal with it later.

Find the provider

Not the balance, not the fund, not the strategy. Just the name of the company holding the account.

It is on the last statement you received, or in your old employer's HR portal if you still have access, or findable by searching your old employer's name alongside the words retirement plan. If all three fail, ask the old HR team directly, because they are required to know.

Everything else, including whether to move it and how, follows from knowing where it is. That is the whole task this week.