A 401(k) is a type of employer-sponsored retirement plan. It allows you to save for retirement using pretax dollars from your paycheck. Frequently, employers will match contributions up to a certain percentage, allowing you to save even more. Then you pay taxes when you take withdrawals from the account in retirement.

How much do you need in a 401(k) to get $1,000 a month in retirement?

You'll need about $300,000 in your 401(k) to be able to withdraw $1,000 per month in retirement. This assumes you follow the 4% rule, which suggests that you withdraw 4% of your savings in the first year of retirement and adjust this amount for inflation in subsequent years.

How much will $10,000 in a 401(k) be worth in 20 years?

This varies depending on your investment rate of return and your fees. If you earned an 8% average annual return over those 20 years, your $10,000 would grow to more than $46,600.

How much should a 25-year-old have in a 401(k)?

This depends on your retirement goals and timeline. One common rule of thumb says you should save 1x your salary by age 30. If you follow this, you likely want to be in the neighborhood of 0.5x your salary by age 25.

What Is a 401(k) and How Does It Work?

By Kailey Hagen – Updated Apr 7, 2026 at 12:47 PM EST | Fact-checked by Parker Hicks

Key Points

401(k) contributions are pre-tax, lowering taxable income and deferred taxes on investment gains.
Employers may match a percentage of your 401(k) contributions, effectively offering free money.
Withdrawal options start at age 59 1/2 usually, with a 10% penalty for earlier access.

If you want to retire someday, and retire well, a 401(k) is one of the most powerful tools available to you. It's a retirement savings account sponsored by your employer that lets you invest a portion of each paycheck, grow that money tax-advantaged, and potentially collect free money from your employer along the way.

Here's everything you need to know to use it well.

What is a 401(k)?

A 401(k) is a retirement savings plan offered through your employer. You contribute a percentage of your paycheck, invest those funds in the market, and benefit from significant tax advantages while your money grows.

The name comes from the section of the IRS tax code that created it -- not the most inspiring origin story, but the account itself is genuinely one of the best wealth-building tools available to working Americans.

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An infographic listing the benefits of 401(k)s, including paycheck deferrals, company matches and potential tax savings. — Image source: The Motley Fool.

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How does a 401(k) work?

When you enroll in your employer's 401(k) plan, you choose a contribution rate, the percentage of your salary that gets deposited into the account each pay period. That money is deducted from your paycheck before income taxes are applied, which lowers your taxable income for the year.

For example, if you earn $60,000 a year and contribute 10%, you're putting $6,000 into your 401(k) annually. But because those contributions are pre-tax, you're not actually losing a full $6,000 from your take-home pay -- the tax savings offset some of the difference.

Once the money is in your account, you invest it. Your plan will offer a menu of investment options, typically mutual funds, index funds, and target-date funds. Your money then grows tax-deferred, meaning you don't owe taxes on dividends, interest, or gains until you withdraw funds in retirement.

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Understanding the employer match and vesting

Many employers sweeten the deal by matching a portion of your contributions. A common structure is a 50% match on contributions up to 6% of your salary, meaning if you contribute 6%, your employer adds another 3% on top.

That's effectively a 50% instant return on part of your investment, which is why financial advisors consistently say: always contribute at least enough to get the full employer match.

However, there's an important catch: vesting schedules. Employer contributions often don't fully belong to you until you've worked at the company for a certain number of years. Common structures include:

Cliff vesting: You own 0% of employer contributions until a set date (often 3 years), then 100% immediately.
Graded vesting: You gradually earn ownership over time. For example, 20% per year over five years.

If you leave a job before you're fully vested, you forfeit the unvested portion of your employer's contributions. Your own contributions are always 100% yours from day one.

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Know your 401(k) contribution limits

The IRS caps how much you can contribute each year. Here are the limits for 2025 and 2026:

Contribution Type	2025 Limit	2026 Limit
Standard employee contribution	$23,500	$24,500
Catch-up contribution (age 50+)	$7,500	$8,000
Super catch-up (ages 60–63)	$11,250	$11,250
Total including employer contributions	$70,000	$72,000

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A few things to keep in mind:

Catch-up contributions are available starting at age 50 and allow you to accelerate savings as retirement nears.
The super catch-up for ages 60–63 is a newer provision under the SECURE Act 2.0.
Total contribution limits include your contributions plus employer matching and any other employer-funded deposits.
You can contribute to both a 401(k) and an IRA in the same year, though income limits may affect IRA deductibility.

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Choose what to invest in

Opening a 401(k) is step one. Choosing how to invest the money is just as important, and where many people get stuck.

Most 401(k) plans offer a menu of funds to choose from. Here's what you'll typically encounter:

Index funds track a broad market index like the S&P 500. They're diversified, low-cost, and tend to outperform actively managed funds over the long run. For most people, a core of index funds is the right starting point.
Target date funds are all-in-one funds that automatically shift toward a more conservative allocation as your target retirement year approaches. They're a solid hands-off option -- just pick the fund closest to your expected retirement year.
Actively managed funds are run by portfolio managers trying to beat the market. They tend to have higher fees (expense ratios) and often underperform index funds over time. Check the expense ratio before investing — anything above 0.5% deserves scrutiny.
Company stock is sometimes offered as an option. Be careful here. Concentrating too much of your retirement savings in your employer's stock means your job and your retirement savings are exposed to the same risk at the same time.

One thing to always check: the expense rat to invest the money is just as important and where many people get stuck. compounds significantly over decades. A $100,000 portfolio with a 1% expense ratio will be worth roughly $30,000 less over 20 years than the same portfolio with a 0.5% expense ratio.

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Understand the Roth 401(k) option

Many employers now offer a Roth 401(k) option alongside the traditional version. The key difference is when you pay taxes:

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	Traditional 401(k)	Roth 401(k)
Contributions	Pre-tax (reduces taxable income now)	After-tax (no immediate tax break)
Investment growth	Tax-deferred	Tax-free
Withdrawals in retirement	Taxed as ordinary income	Tax-free
RMDs	Required starting at age 73	No longer required (as of 2024)

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Which should you choose? A useful rule of thumb:

If you expect to be in a lower tax bracket in retirement than you are now, the traditional 401(k) is likely better. You get the deduction when it's most valuable.
If you expect to be in a higher tax bracket in retirement, or you're early in your career and currently in a low bracket, the Roth 401(k) often makes more sense. You pay taxes now at a lower rate and enjoy tax-free growth for decades.
If you're unsure, splitting contributions between traditional and Roth gives you tax diversification in retirement.

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Know the withdrawal rules

The 401(k) is designed for retirement, and the IRS enforces that with penalties for early access.

Standard withdrawals: You can take penalty-free withdrawals starting at age 59½. If you leave your employer at age 55 or older, you may be able to access the funds penalty-free under the "Rule of 55."

Early withdrawals: Withdrawals before age 59½ are generally subject to a 10% penalty plus ordinary income taxes. Exceptions include:

Permanent disability
Substantial medical expenses
Substantially equal periodic payments (SEPP/72(t) distributions)
Qualified domestic relations orders (divorce settlements)
Death (distributions to beneficiaries)

Required minimum distributions (RMDs): Starting at age 73, you must begin taking annual withdrawals from a traditional 401(k) whether you need the money or not. The amount is calculated based on your account balance and life expectancy. Roth 401(k)s are no longer subject to RMDs as of 2024.

401(k) loans: Some plans allow you to borrow against your balance — typically up to 50% of your vested balance or $50,000, whichever is less. You repay yourself with interest, but if you leave your job, the loan usually becomes due by your next tax filing deadline. Unpaid loans are treated as distributions and taxed accordingly.

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How to do a withdrawal from a 401(k)

Understand all the ways you can take money out of your 401(k)

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401(k) rollovers

When you leave a job, you have four options for your 401(k):

Roll it into your new employer's 401(k): Simple and keeps everything consolidated
Roll it into an IRA: Often gives you more investment options and potentially lower fees
Leave it with your former employer: Allowed in most cases if your balance is above $5,000, but you lose the ability to make new contributions
Cash it out: Almost always the wrong move; you'll owe income taxes plus a 10% penalty if you're under 59½

If you do roll over, always opt for a direct rollover -- your plan administrator sends the money straight to the new account. If the check comes to you instead, 20% will be withheld for taxes, and you'll have 60 days to deposit the full original amount (including the withheld portion) into a new account or face taxes and penalties on the difference.

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What if your employer doesn't offer a 401(k)?

Not everyone has access to an employer-sponsored plan. If that's your situation:

Traditional or Roth IRA: Contribution limits are lower ($7,000 in 2025 and 2026, plus $1,000 catch-up if 50+), but these accounts offer strong tax advantages and broad investment flexibility.
SEP-IRA or Solo 401(k): If you're self-employed or have freelance income, these options allow significantly higher contribution limits.
Taxable brokerage account: No tax advantages, but no contribution limits either; a good option once you've maxed tax-advantaged accounts.

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The bottom line

The 401(k) is one of the most effective wealth-building tools available, especially when you start early, capture the full employer match, keep fees low, and let compound growth do its work over decades. The mechanics take a few hours to understand. The payoff lasts a lifetime.

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401(k) FAQs

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About the Author

Kailey Hagen, CFP, is a contributing Motley Fool retirement analyst covering Social Security, Medicare, and retirement planning. Before The Motley Fool, Kailey was a research analyst for Reviews.com focusing on credit and banking products. She is a Certified Financial Planner® and holds a bachelor’s degree in English from the University of Wisconsin-Madison.

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The Motley Fool has a disclosure policy.

What Is a 401(k) and How Does It Work?

Key Points

What is a 401(k)?

How does a 401(k) work?

Understanding the employer match and vesting

Know your 401(k) contribution limits

Choose what to invest in

Understand the Roth 401(k) option

Know the withdrawal rules

401(k) rollovers

What if your employer doesn't offer a 401(k)?

The bottom line

401(k) FAQs

What is a 401(k)?

How much do you need in a 401(k) to get $1,000 a month in retirement?

How much will $10,000 in a 401(k) be worth in 20 years?

How much should a 25-year-old have in a 401(k)?

About the Author

Read Next

Premium Investing Services

What is a 401(k)?

How does a 401(k) work?

Understanding the employer match and vesting

Choose what to invest in

Understand the Roth 401(k) option

Know the withdrawal rules

401(k) rollovers

What if your employer doesn't offer a 401(k)?

The bottom line

401(k) FAQs

What is a 401(k)?

How much do you need in a 401(k) to get $1,000 a month in retirement?

How much will $10,000 in a 401(k) be worth in 20 years?

How much should a 25-year-old have in a 401(k)?