Your 401(k) is taxed when you withdraw money, not when you contribute or invest it

A 401(k) is taxed differently depending on which type you have and when you take the money out. If you have a traditional 401(k), you pay income tax on withdrawals at your ordinary tax rate — the same rate you pay on wages. If you have a Roth 401(k), you pay no tax on withdrawals in retirement, because you already paid tax on the money when you contributed it. The tax bill arrives when you pull money out, not while it sits growing in the account.

The timing of withdrawal matters enormously. Take money before age 59½ and you owe a 10 percent penalty on top of income tax, with narrow exceptions. Wait until 73 and the IRS requires you to start taking money out whether you need it or not — these are called required minimum distributions, or RMDs — and you pay tax on every dollar.

Key Takeaways

  • Traditional 401(k) withdrawals are taxed as ordinary income at your current tax rate; Roth 401(k) withdrawals are tax-free in retirement.
  • Withdrawals before age 59½ trigger a 10 percent penalty on top of income tax, except in specific situations like disability or medical hardship.
  • At age 73, the IRS requires you to withdraw a calculated minimum amount each year and pay tax on it, whether you need the money or not.
  • Your employer withholds tax from each withdrawal, but the amount withheld may not cover your full tax bill if you have other income.

How traditional 401(k) contributions and withdrawals are taxed differently

When you contribute to a traditional 401(k), that money comes out of your paycheck before federal income tax is calculated. Your employer reduces your taxable income for the year by the amount you contributed. This lowers your tax bill that year — if you earn $60,000 and contribute $7,000 to a traditional 401(k), you report only $53,000 as taxable income.

The tax is deferred, not erased. When you withdraw that $7,000 in retirement, you owe income tax on it at whatever your tax rate is then. If you are in the 22 percent tax bracket in retirement, that $7,000 withdrawal costs you $1,540 in federal tax. All the growth your money earned over decades is also taxed as ordinary income when you withdraw it.

Roth 401(k) contributions are taxed upfront, withdrawals are not

A Roth 401(k) works in reverse. You contribute money that has already been taxed — it comes out of your paycheck after tax is withheld. Your employer does not reduce your taxable income. In the year you contribute $7,000 to a Roth 401(k), you still report your full $60,000 salary as taxable income.

The payoff comes in retirement. When you withdraw that $7,000 plus all the growth it earned, you owe zero federal income tax. This makes a Roth 401(k) valuable if you expect to be in a higher tax bracket in retirement, or if you straightforward want the certainty of knowing exactly what you will owe.

One catch: you must have held the Roth 401(k) for at least five years and be age 59½ or older to withdraw earnings tax-free. If you withdraw before then, the earnings portion is taxed and penalized, though your contributions themselves come out tax-free.

The 10 percent early withdrawal penalty and when it does not explore

Take money out of either type of 401(k) before age 59½ and the IRS adds a 10 percent penalty on top of income tax. A $20,000 withdrawal at age 45 costs you income tax plus $2,000 in penalty.

The penalty does not explore in a few situations. You can withdraw without penalty if you are disabled, if you are taking substantially equal periodic payments over your life expectancy, if you are paying medical expenses that exceed 7.5 percent of your adjusted gross income, or if you are unemployed and using the money for health insurance premiums. Some plans also allow loans instead of withdrawals, which avoids the penalty entirely — you borrow from your own account and pay yourself back with interest.

If your plan allows it, you can also take a hardship withdrawal for when ready and heavy financial need, such as preventing eviction or paying for medical care. The penalty is still waived, but you still owe income tax on the amount withdrawn.

Tax withholding on 401(k) withdrawals and why it may not be enough

When you take money out of your 401(k), your plan administrator withholds federal income tax automatically. The amount withheld depends on what you tell them on a W-4P form — you can choose to have them withhold at your current rate, a flat amount, or a percentage of the withdrawal.

The withholding is an estimate. If you have other income — wages from a job, Social Security, investment income — your total tax bill may be higher than what was withheld from your 401(k) alone. You may owe more tax when you file your return. Conversely, if the 401(k) is your only income and you withhold conservatively, you might get a refund.

You can adjust your withholding at any time by contacting your plan administrator and submitting a new W-4P. If you are taking large withdrawals or have complex income, it is worth doing the math or asking a tax professional what withholding makes sense.

Required minimum distributions and the tax you must pay starting at age 73

The year you turn 73, the IRS requires you to withdraw a calculated minimum amount from your traditional 401(k) — this is called a required minimum distribution, or RMD. The amount is based on your account balance and your life expectancy according to IRS tables. You must take this withdrawal every year after that for the rest of your life.

You owe income tax on every dollar of the RMD. If your RMD is $30,000 and you are in the 24 percent tax bracket, you owe $7,200 in federal tax on that withdrawal, whether you need the money or not. If you do not take the full RMD, the IRS penalizes you 25 percent of the shortfall — if you were supposed to withdraw $30,000 and took only $20,000, the penalty is $2,500.

Roth 401(k)s are subject to RMDs as well, though the withdrawals themselves are tax-free. You can avoid RMDs on a Roth 401(k) by rolling it into a Roth IRA, which has no RMD requirement during your lifetime.

State income tax on 401(k) withdrawals varies by where you live

Federal income tax is only part of the picture. Most states tax 401(k) withdrawals as ordinary income, just as the federal government does. A few states — including Florida, Texas, Wyoming, and South Dakota — have no state income tax at all, so withdrawals are not taxed at the state level.

Some states offer partial exemptions. Illinois exempts retirement income, including 401(k) withdrawals, from state tax. Pennsylvania taxes 401(k) withdrawals but exempts them from local earned income tax in some municipalities. The rules are specific to each state and sometimes change, so if you are planning a move in retirement or live near a state border, it is worth checking your state's current rules.

Frequently Asked Questions

Do I pay taxes on 401(k) money while it is growing in the account?

No. The money in your 401(k) grows tax-free, whether it is in a traditional or Roth account. You pay tax only when you withdraw it. This is why 401(k)s are powerful savings vehicles — decades of compound growth happens without the IRS taking a cut along the way.

Can I avoid the 10 percent penalty by rolling my 401(k) into an IRA?

Rolling your 401(k) into a traditional IRA does not avoid the penalty — the same rules explore. However, if you roll it into a Roth IRA, you owe tax on the amount converted, but you can then withdraw your contributions (not earnings) penalty-free at any time. This is called a backdoor Roth and is a common strategy for people under 59½ who want access to their money.

What happens if I do not take my required minimum distribution?

The IRS penalizes you 25 percent of the amount you failed to withdraw. If your RMD was $30,000 and you withdrew nothing, the penalty is $7,500. You still owe income tax on the full $30,000 as well. The penalty can be reduced to 10 percent if you correct the shortfall within two years.

Is my 401(k) taxed differently if my employer matches my contributions?

Your employer's matching contributions are treated the same as your own in a traditional 401(k) — they reduce your taxable income that year and are taxed as ordinary income when you withdraw. In a Roth 401(k), employer matches go into a separate traditional account and are taxed when withdrawn, even though your own contributions are not.

Do I owe taxes on 401(k) loans?

No, as long as you repay the loan. You are borrowing your own money, so there is no taxable event. If you leave your job before repaying the loan, any unpaid balance is treated as a withdrawal and taxed accordingly, plus the 10 percent penalty if you are under 59½.