How your 401(k) is taxed in retirement depends on the type. A traditional 401(k) defers the tax bill: you skip tax on the way in, and withdrawals in retirement are taxed as ordinary income. A Roth 401(k) settles it now, so qualified withdrawals come out tax-free.

How a traditional 401(k) is taxed

A traditional 401(k) gives you the tax break up front. Contributions come from pre-tax pay, which lowers your taxable income for the year, and the account grows tax-deferred, so you owe nothing on contributions or earnings until you withdraw.

Here is what the pre-tax reduction looks like: earn $100,000 in 2026 and contribute the maximum of $24,500, or more with a catch-up contribution, and the IRS taxes you on $75,500 of income that year.

In retirement, every withdrawal from a traditional 401(k) is taxed as ordinary income at your bracket that year. There is no separate capital-gains treatment on the growth; it all comes out as income.

How a Roth 401(k) is taxed

A Roth 401(k) reverses the timing. You contribute after-tax dollars, so there is no deduction now, but qualified withdrawals in retirement, including all the growth, are tax-free.

To be qualified, a withdrawal must meet two conditions: the account must be at least five years old, and you must be at least 59 1/2. Death or disability can substitute for the age requirement and removes the 10% early-withdrawal penalty, but the five-year rule is separate and still applies. If the account is not yet five years old, the earnings portion is still taxable, whether the owner or a beneficiary is withdrawing. See what qualifies as a Roth 401(k) withdrawal for the full breakdown.

One catch: employer matching money is always pre-tax, even in a Roth 401(k). It sits in a companion traditional account and is taxed as ordinary income when you withdraw it.

Traditional 401(k) vs. traditional IRA

The two share the same core tax treatment: pre-tax contributions that lower your taxable income now, tax-deferred growth, and ordinary income tax on withdrawals in retirement. There is no difference in the tax rate applied to withdrawals.

Which is better depends on other factors: whether your employer offers a match (only the 401(k) does), how much investment control you want (the IRA offers more), and how much you want to contribute (the 401(k) limit is far higher). Many people use both.

Strategies to lower the tax on 401(k) withdrawals

Delay withdrawals until you need them

If you can leave the money alone, it keeps growing tax-deferred. Keep in mind that required minimum distributions begin at age 73 if you were born between 1951 and 1959, or age 75 if you were born in 1960 or later.

Use Roth conversions strategically

Converting part of a traditional 401(k) or IRA to a Roth means paying tax on the converted amount now for tax-free withdrawals later. Converting smaller amounts over several years, often in early retirement before Social Security and RMDs start, keeps each year's conversion from pushing you into a higher bracket.

Manage your tax bracket

Plan withdrawals to stay inside a target bracket, coordinating 401(k) distributions with Social Security and taxable-account income so you don't cross into a higher rate.

Rolling over a 401(k)

When you leave a job, you decide what to do with the 401(k). While employed, most plans won't let you move the funds; once you leave, you have full control.

The simplest and most tax-efficient move is a direct rollover, which sends the money straight from the old 401(k) into an IRA or your new employer's 401(k) with no tax withheld. If you take the check yourself and don't redeposit it within 60 days, the IRS treats it as a withdrawal: income tax, plus a 10% penalty if you're under 59 1/2.

You can also roll a pre-tax 401(k) into a Roth IRA, which is a Roth conversion. You owe tax on the full amount converted that year, and a large conversion can bump your bracket. After that, the money grows and comes out tax-free.

Moving an old 401(k) into a new employer's plan is another option if their plan allows it, and it keeps everything in one place.

Company stock and Net Unrealized Appreciation

If your 401(k) holds company stock, the Net Unrealized Appreciation (NUA) strategy can lower your tax. You move the stock into a taxable brokerage account rather than an IRA, pay ordinary income tax only on the stock's original cost basis, and pay the lower long-term capital gains rate on the appreciation when you eventually sell.

NUA works best when the stock has grown a lot since you acquired it. The rules are intricate, so work with a tax advisor before acting.

Final thoughts

With a traditional 401(k), expect to pay income tax on your withdrawals in retirement; with a Roth 401(k), the tax was already paid. Knowing which applies, and planning the timing of withdrawals, rollovers, and conversions, is what keeps the tax bill from surprising you. A Certified Financial Planner can model the options against your full income picture, including how a Roth IRA fits alongside your 401(k).

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