What Is a 401(k)? How It Works, 2026 Limits and the Employer Match

What Is a 401(k)?

A 401(k) is a workplace retirement plan that lets you invest part of your wages in an account in your name. The Internal Revenue Service (IRS) describes it as a feature of a qualified profit-sharing plan that allows employees to contribute a portion of their wages to individual accounts.² The name comes from the section of the US tax code that created it.

Your contributions come out of your paycheck automatically, before you ever see the money. They are then invested, usually in a menu of funds your employer’s plan offers. Over decades, those regular contributions and their investment growth can add up to a large part of your retirement income.

Many employers also contribute to their employees’ accounts, most often as a match on what you put in.² That is one of the main reasons financial educators encourage people to join their workplace plan early.

How a 401(k) Works, Step by Step

Once you sign up, a 401(k) runs largely on autopilot.

1. You choose a contribution. Usually a percentage of your pay, such as 6%.
2. Your employer deducts it from each paycheck. The money goes straight into your account.
3. Your employer may add money. Many plans match part of what you contribute.
4. The money is invested. You pick funds from the plan’s menu, or a default fund such as a target-date fund.
5. It grows until retirement. Gains are not taxed each year while they stay in the account.

The 2026 401(k) Contribution Limits

The IRS sets yearly limits on how much can go into a 401(k), and raises them with inflation. These are the figures for 2026.¹³

The total limit is the lower of $72,000 or 100% of your pay, and it rises to $80,000 with the standard catch-up, or $83,250 for those aged 60 to 63.³ Most people never come close to these caps. They matter mainly for high earners and people with generous employer contributions.

Traditional vs Roth 401(k)

Many plans offer two kinds of contributions, and the difference is when you pay tax.

The IRS explains that traditional deferrals are excluded from taxable income and taxed when withdrawn, while qualified distributions from designated Roth accounts are not included in taxable income.² Both types share the same $24,500 employee limit for 2026, so you can split your savings between them.

If you are early in your career and in a low tax bracket, Roth contributions can be attractive. If you are in a high bracket now, the immediate tax saving from traditional contributions may be worth more. Our explainer on how tax brackets work shows how to find your marginal rate.

The Employer Match: Free Money for Retirement

An employer match is money your employer adds to your account when you contribute. A common formula is 50 cents for every dollar you put in, up to 6% of your pay, but plans vary widely. Check your plan documents for your own formula.

Here is an illustration. Someone earning $60,000 contributes 6%, or $3,600 a year. With a 50% match up to 6% of pay, the employer adds $1,800. That is an immediate 50% return on the money contributed, before any investment growth.

Not contributing enough to get the full match means leaving part of your pay on the table. For that reason, “contribute at least enough to get the whole match” is one of the most common pieces of retirement advice.

Vesting: when the match becomes yours

Your own contributions are always yours. Employer contributions may follow a vesting schedule, which means you must work there for a set time before they are fully yours. If you leave early, you may lose some unvested employer money. Your plan’s summary will show its schedule.

A Worked Example: What Steady Saving Can Become

Regular contributions plus a match plus decades of growth can produce a large balance. In this illustration, the person above saves $300 a month and receives a $150 monthly match, for $450 a month in total. The investments earn 7% a year, which is an assumption, not a forecast.

After 30 years, about $162,000 has gone in. With growth, the balance reaches roughly $549,000. If the same person saved for 35 years instead, the balance would be about $810,000, showing how much the final years of compounding add.

Real investment returns vary from year to year, and fees reduce growth, so the actual result would be different. Our compound interest calculator lets you test your own numbers, and our explainer on compound interest shows why starting early matters so much.

What You Can Invest In

A 401(k) is an account, not an investment, so what you hold inside it matters. Plans offer a menu of funds, typically including stock funds, bond funds and target-date funds.

A target-date fund holds a mix of stocks and bonds and gradually shifts toward bonds as its target year, usually your expected retirement year, approaches. Many plans use one as the default for people who do not choose. Broad, low-cost index funds are another common choice, because fees compound against you over long periods.

Review the fees for each fund in your plan. Two funds that look similar can charge very different amounts each year.

Withdrawals and the Age 59½ Rule

A 401(k) is designed for retirement, so taking money out early usually costs extra. The IRS generally treats withdrawals from a qualified plan before age 59½ as early distributions, which face a 10% additional tax on the taxable amount.⁴ That is on top of regular income tax for traditional money.

There are exceptions, which the IRS lists, such as certain disability or medical situations.⁴ Some plans also offer loans or hardship withdrawals, each with its own rules and costs. Treat these as a last resort, because money taken out stops growing for your retirement.

Later in life, the rules change in the other direction. Traditional 401(k) money must eventually be withdrawn under required minimum distribution rules, so check the current IRS guidance as you approach your seventies.

What Happens When You Change Jobs

Your 401(k) money stays yours when you leave an employer, at least the part that is vested. You usually have several choices:

• Leave it in your old plan, if the plan allows and your balance is large enough.
• Roll it into your new employer’s plan, if the new plan accepts rollovers.
• Roll it into an IRA, which can give you a wider choice of investments.
• Cash it out, which usually triggers income tax and, before 59½, the 10% additional tax.

A direct rollover, where the money moves straight from one plan or provider to another, avoids accidental taxes and withholding. Cashing out a small balance can feel harmless, but it gives up years of tax-advantaged growth.

401(k) vs IRA

Both are tax-advantaged retirement accounts, but a 401(k) comes through your job and an IRA you open yourself. For 2026, a 401(k) allows up to $24,500 in employee contributions, while an IRA allows $7,500.¹

A 401(k) can include an employer match, which an IRA does not. An IRA usually offers a wider choice of investments. Many people use both: first contributing enough to their 401(k) to get the full match, then adding to an IRA or putting more into the 401(k), depending on fees and investment choices.

Automatic Enrollment and Escalation

Many employers now sign new workers up for the 401(k) automatically. With automatic enrollment, a set percentage of your pay goes into the plan unless you choose a different amount or opt out. The money usually goes into a default investment, often a target-date fund.

Some plans also raise your contribution rate a little each year, a feature often called automatic escalation. Both features help people save without having to make an active decision, which matters because many people never get round to signing up on their own.

If you were enrolled automatically, check the default rate. It may be lower than the rate needed to get your employer’s full match.

Fees Inside a 401(k)

Every 401(k) has costs, and they come out of your balance whether you notice them or not. There are usually two layers: the expense ratio of each fund you hold, and plan administration fees for record-keeping and services.

A difference of half a percentage point a year can mean many thousands of dollars less at retirement, because the fee is charged on a growing balance every year. Your plan must give you information about its fees. Look for low-cost index funds on the menu if they are available.

Reading Your 401(k) Statement

Your statement shows where your money came from and how it is invested. Look for four things: your own contributions, your employer’s contributions, your vested balance and your investment returns.

The vested balance is the part you would keep if you left today. The investment mix shows how much is in stocks, bonds and cash. Checking these once or twice a year is enough for most people, rather than reacting to every market move.

How a 401(k) Fits With Social Security

For most Americans, retirement income comes from several sources, and a 401(k) is usually one of the largest you control. Social Security provides a base income, but it is designed to replace only part of what you earned while working.

A 401(k), an IRA and other savings fill the gap. The earlier you start, the more of that gap regular contributions and compound growth can cover.

How Much Should You Contribute?

There is no single right number, but there is a sensible order of priorities.

1. Get the full match. Contribute at least enough to receive every dollar your employer offers.
2. Build an emergency cushion. Money you can reach without penalties protects you from early withdrawals.
3. Clear high-interest debt. Credit card interest usually costs more than investments are likely to earn.
4. Raise your rate over time. Many plans let you increase your contribution automatically by 1% a year, often timed with raises.

Increasing your rate when you get a raise is one of the least painful ways to save more, because your take-home pay still goes up.

Common 401(k) Mistakes

A few common errors cost people far more than they realize.

• Not joining at all, or waiting years to start.
• Missing part of the match by contributing too little.
• Cashing out when changing jobs, paying tax and losing decades of growth.
• Ignoring fees, which compound against your balance every year.
• Selling in a panic when markets fall, locking in losses instead of riding out the recovery.

Key Terms Explained

• Elective deferral: the part of your pay you choose to put into the plan.
• Employer match: money your employer adds based on what you contribute.
• Vesting: the schedule that decides when employer contributions become fully yours.
• Catch-up contribution: extra contributions allowed from age 50.
• Rollover: moving retirement money from one plan or account to another without cashing it out.
• Target-date fund: a fund that becomes more conservative as a chosen year approaches.

The Bottom Line

A 401(k) turns small, automatic paycheck savings into long-term retirement money, often with help from your employer. Join early, get the full match, keep fees low and leave the money invested. Check the IRS limits each year, and think about the traditional or Roth choice based on your tax rate now and later. For more, browse our investing explainers.

Wondering whether you are on track? Our guide to how much to save for retirement by age sets out checkpoints from 30 to 67.

Saving outside work too? Our explainer on Roth IRAs covers the 2026 limits and rules.

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