401(k) Tax Rules: Contributions, Growth, & Withdrawals

April 13, 2026

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A 401(k) is one of the most common ways to build retirement savings while taking advantage of favorable tax treatment. Understanding how it works—and where people often make mistakes—can help you use it more effectively.

Are 401(k) contributions pre-tax?

Most workplace plans allow multiple contribution types. With a traditional 401(k), contributions are made before income taxes are applied, reducing your taxable income today. A Roth 401(k), by contrast, is funded with after-tax dollars, meaning you pay taxes now in exchange for potential tax-free withdrawals later. Some plans also permit separate after-tax contributions, which follow their own rules.

For 2026, the employee contribution limit is $24,500, whether contributions are pre-tax or Roth. If you’re age 50 or older, you can contribute an additional $8,000—or $11,250 if you’re between ages 60 and 63. In some cases, total contributions (including employer contributions and after-tax amounts) can reach $72,000.

Under provisions of the SECURE 2.0 Act, individuals earning more than $150,000 (based on prior-year FICA wages) must make catch-up contributions as Roth contributions. If a plan doesn’t offer a Roth feature, those individuals may not be eligible to make catch-up contributions at all.

Are 401(k) contributions tax-deductible?

Technically, traditional 401(k) contributions are not deducted on your tax return. Instead, they reduce your taxable income upfront because they are taken from your paycheck before taxes are calculated. This lowers your overall tax liability indirectly.

Roth contributions do not provide a current-year tax benefit, since taxes are paid before the money goes into the account. However, the tradeoff is the potential for tax-free income in retirement.

Do you pay taxes on a 401(k) while it grows?

One of the primary advantages of a 401(k) is tax-deferred growth. With a traditional 401(k), you won’t owe taxes on interest, dividends, or capital gains while the money remains in the account. Taxes are deferred until you take distributions.

Roth 401(k)s also allow for tax-advantaged growth, but qualified withdrawals—including earnings—can be tax-free rather than merely tax-deferred. Required minimum distributions (RMDs) generally begin at age 73 for traditional accounts, though Roth 401(k)s are not subject to RMDs during the original owner’s lifetime.

How are traditional and Roth 401(k)s taxed differently?

The key distinction is timing. Traditional 401(k) contributions reduce taxable income today, but withdrawals are taxed as ordinary income in retirement. Roth 401(k) contributions are made after taxes, but qualified withdrawals can be taken tax-free.

This difference can influence long-term tax planning. Traditional accounts may provide relief during high-earning years, while Roth accounts can offer flexibility and tax efficiency later in life.

What is an after-tax 401(k)?

Some plans allow additional after-tax contributions beyond the standard limits. These contributions don’t reduce your taxable income, but any earnings grow tax-deferred. When withdrawn, contributions come out tax-free, while earnings are taxed as income.

Are withdrawals from a 401(k) taxable?

Withdrawals from a traditional 401(k) are generally subject to ordinary income tax. While you can begin taking distributions without penalty at age 59½, early withdrawals typically trigger a 10% penalty in addition to taxes.

There are exceptions, including disability, certain birth or adoption expenses, and the “rule of 55,” which allows penalty-free withdrawals if you leave your employer in or after the year you turn 55. Another option is a structured withdrawal approach known as substantially equal periodic payments (SEPP), though it comes with strict requirements.

Are any 401(k) withdrawals tax-free?

Traditional 401(k) withdrawals are always taxable. However, Roth 401(k) distributions may be tax-free if they meet two conditions: you are at least age 59½ and the account has been open for at least five years. If those requirements aren’t met, a portion of the withdrawal—specifically the earnings—may be subject to taxes and penalties.

What tax rate applies to withdrawals?

Distributions from a traditional 401(k) are taxed as ordinary income, meaning your rate depends on your overall taxable income in the year of withdrawal. Federal rates currently range from 10% to 37%.

Strategies to manage taxes in retirement

There are several ways to potentially reduce the tax impact of withdrawals:

●     Diversify account types: Having a mix of taxable, tax-deferred, and tax-free accounts can give you flexibility in managing your tax bracket.

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●     Consider Roth conversions: Converting some pre-tax assets to Roth accounts may create future tax-free income, though the conversion itself is taxable.

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●     Plan for heirs: Roth assets can be more tax-efficient for beneficiaries, depending on the circumstances.

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●     Use a QLAC: A Qualified Longevity Annuity Contract can delay a portion of required distributions, which may help manage taxable income later in life.

Are rollovers taxable?

Moving funds from one retirement account to another—such as from a 401(k) to an IRA—is typically not a taxable event if done correctly. Direct rollovers avoid withholding and penalties. However, converting pre-tax funds to a Roth account does trigger taxes in the year of conversion.

Do you need to report your 401(k) on your taxes?

You don’t report contributions or earnings that remain in the account. However, any withdrawals must be reported as income. Your plan provider will issue the necessary forms, such as Form 1099-R, to help with reporting.

Final takeaway

A 401(k) can be a powerful tool for retirement planning, but the tax rules are nuanced. Understanding how contributions, growth, and withdrawals are taxed allows you to make more informed decisions—both now and in the future.

Sources:

https://www.fidelity.com/learning-center/personal-finance/retirement/401k-taxes

Disclosure:

This information is an overview and should not be considered as specific guidance or recommendations for any individual or business.

This material is provided as a courtesy and for educational purposes only.

These are the views of the author, not the named Representative or Advisory Services Network, LLC, and should not be construed as investment advice. Neither the named Representative nor Advisory Services Network, LLC gives tax or legal advice. All information is believed to be from reliable sources; however, we make no representation as to its completeness or accuracy. Please consult your Financial Advisor for further information.

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