P 401(k) Plan Report

401(k) Basics

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

A 401(k) is a workplace retirement plan that combines payroll saving, tax advantages, investments and often employer contributions. Here is what matters in practice.

401(k) Plan Report Editorial TeamPublished May 8, 2026Reviewed August 25, 202612 minute read

A 401(k) is a retirement account built into your paycheck.

You choose how much of your pay to contribute. The employer sends that money into the plan. You invest it among the options the plan offers. In many plans, the employer adds money too. The account can then grow for years or decades with tax advantages that depend on whether your contributions are traditional pre-tax or Roth.

That is the basic idea.

The details—match, vesting, fees, investment menu, eligibility, loans and withdrawal rules—are where one employer's 401(k) can become much better or worse than another's.

Quick answer:** A 401(k) is an employer-sponsored defined contribution retirement plan. Employees can defer part of their pay into the plan, often on a pre-tax and/or Roth basis. Employers may make matching or other contributions. The employee chooses among the plan's investments, and the eventual retirement benefit depends on contributions, investment results, fees and withdrawals—not on a guaranteed pension formula.

Why is it called a 401(k)?

The name comes from Section 401(k) of the Internal Revenue Code.

That is why the punctuation looks odd. It is a tax-code reference that became the everyday name for one of America's most common workplace retirement arrangements.

The IRS's 401(k) participant overview ↗ explains the federal framework.

How a 401(k) works, step by step

1. Your employer offers the plan

A 401(k) is tied to an employer. You do not independently open a 401(k) at a brokerage the way you open an IRA.

The employer adopts the plan and chooses service providers, investment options and plan features within federal rules.

2. You become eligible

Some plans let employees participate immediately. Others have age, service or entry-date requirements.

Automatic enrollment has become increasingly common, so you may be enrolled at a default contribution rate unless you opt out or change it.

3. You choose a contribution rate

You might contribute 3%, 6%, 10% or a flat dollar amount from each paycheck, subject to plan and federal limits.

For 2026, the regular employee elective-deferral limit is $24,500. Catch-up contributions can allow more for older participants.

See the full 2026 401(k) contribution limits.

4. The employer may contribute

Many employers match part of what employees contribute. Others make nonelective or profit-sharing contributions. Some do both. Some contribute nothing.

The employer formula is part of your compensation package.

5. You choose investments

A 401(k) is the account structure, not the investment itself.

Inside the plan, you may have access to:

Your balance changes with contributions, withdrawals, fees and investment results.

6. The money stays in the plan until you use or move it

401(k)s are designed for retirement. Early access can be restricted and may trigger taxes.

Plans can permit loans or hardship distributions, but they are not required to.

When you leave the employer, you may have options to keep the money in the plan, roll it to another plan or IRA, or take a distribution.

Traditional 401(k) vs. Roth 401(k)

Many plans offer both.

Traditional 401(k)

Employee elective deferrals generally reduce current federal taxable income, subject to the tax rules. The money grows tax-deferred, and taxable distributions are generally included in income later.

Roth 401(k)

Roth employee contributions are made after tax. Qualified Roth distributions can be tax-free if the applicable requirements are satisfied.

The two contribution types share the same employee elective-deferral limit.

If the 2026 limit is $24,500, you cannot generally contribute $24,500 pre-tax plus another $24,500 Roth. The combined elective deferrals are subject to the limit.

Neither tax treatment is universally better. Current tax rate, expected future rate, income, retirement plan and estate goals all matter.

What is a 401(k) match?

A match is employer money tied to your employee contribution.

Example:

Your employer matches 50% of the first 6% of salary you contribute.

You earn $80,000 and contribute 6%, or $4,800.

The employer contributes 50% of $4,800, or $2,400.

The maximum employer match in that formula is therefore 3% of pay, not 6%.

This is why match language needs to be translated into dollars.

Vanguard's How America Saves 2026 data found an average maximum promised match of 4.7% of pay and a median of 4.0% among the plans in its matching-formula analysis.

Read our complete guide to the average 401(k) match.

Go beyond the benefits brochure:** Search your employer to see what the retirement plan reported in public filings. Use a current plan document for match, vesting and investment terms.

What does vesting mean?

Vesting determines ownership of certain employer contributions.

Your own employee contributions are always 100% vested.

Employer contributions may be:

If you leave the employer before becoming fully vested, you can forfeit the unvested employer amount.

That is why the total account balance shown in the portal can be higher than the vested balance.

Read what vested means in a 401(k) before changing jobs.

What is the 401(k) contribution limit in 2026?

The regular employee elective-deferral limit is $24,500 in 2026.

If the plan permits catch-up contributions:

There is also a separate $72,000 overall annual-additions limit that can include employee contributions, employer contributions and certain other additions, before catch-up contributions.

The limit is a maximum, not a savings recommendation.

How much should you contribute to a 401(k)?

There is no single correct percentage.

A practical starting point is to understand the employer contribution.

If the employer matches dollar-for-dollar on the first 4% of pay and you contribute only 2%, you may be leaving part of the offered employer benefit unused.

When cash flow permits, many employees prioritize contributing enough to receive the full available match, then decide how additional retirement saving fits with:

A 401(k) contribution that causes you to carry expensive credit-card debt every month can be counterproductive even if the retirement tax benefit is attractive.

What happens to the money after you contribute?

Your contribution is invested according to your elections.

If you do not choose investments, many plans place contributions into a qualified default investment alternative, often a target-date fund.

The account balance can rise or fall with the markets.

A 401(k) is not a guaranteed-return savings account. The eventual value depends heavily on:

Two employees in the same company 401(k) can have very different outcomes because they contribute and invest differently.

How do 401(k) fees work?

There is no single “401(k) fee.”

Costs generally fall into three groups:

Administrative fees

Plan recordkeeping, compliance, accounting, legal, audit and similar operating expenses.

Investment fees

The expense ratios and other costs of the funds or investments you select.

Individual service fees

Loan fees, distribution fees, managed-account charges and similar participant-specific costs.

The Department of Labor tells participants to consider fees alongside the services and investments received.

Our 401(k) fee guide shows where to find the costs and how to compare employers.

Can you lose money in a 401(k)?

Yes.

A 401(k) account invested in stocks, bonds and other market assets can decline in value.

That does not mean the 401(k) “failed.” It means the investments carry market risk.

What matters is whether your allocation fits your time horizon and risk tolerance, whether the plan provides reasonable diversified options and whether you avoid making impulsive decisions during market declines.

The plan's total asset change is also not your personal investment return. Plan assets move because of contributions, withdrawals, transfers and market performance across thousands of participants.

Can you withdraw money before retirement?

Sometimes, but 401(k)s restrict access because they are intended for retirement.

A plan may permit distributions after events such as:

Early taxable distributions can face an additional 10% federal tax unless an exception applies.

The rules depend on the reason for the distribution and the plan.

What is a 401(k) hardship withdrawal?

A plan may allow a distribution for an immediate and heavy financial need under the hardship rules.

The money generally does not return to the account and can be taxable.

Qualifying categories can include certain medical expenses, home-purchase costs, tuition, eviction or foreclosure prevention, funeral expenses and qualifying disaster-related needs.

See our 401(k) hardship withdrawal guide before using retirement money for an emergency.

What is a 401(k) loan?

If the plan allows it, you may be able to borrow against part of your vested account balance.

Federal rules generally limit the loan to the lesser of $50,000 or 50% of the vested account balance, subject to additional rules and plan restrictions.

Most loans must be repaid within five years, with a possible longer term for a principal-residence purchase.

A loan can avoid an immediate taxable distribution when the rules are followed, but it reduces invested assets and can become complicated when you leave the employer.

Read our 401(k) loan guide.

What happens to your 401(k) when you change jobs?

You generally have several options for the vested balance:

Do not automatically cash it out.

Do not automatically roll it to an IRA either.

Compare fees, investments, plan protections and withdrawal rules. If you are around age 55, the Rule of 55 can make the old employer plan particularly important.

See what happens to a 401(k) when you leave a job.

401(k) vs. IRA

A 401(k) is employer-sponsored. An IRA is individually established.

A 401(k) generally offers:

An IRA generally offers:

It is common to use both rather than choose one permanently.

401(k) vs. pension

A traditional pension is a defined benefit plan: the employer promises a benefit determined under a formula, often based on pay and years of service.

A 401(k) is a defined contribution plan: contributions go into an individual account, and the final value depends on contributions, investments, fees and withdrawals.

That shifts more investment and savings responsibility to the employee.

How to tell if your employer's 401(k) is good

Do not judge it on the match alone.

A strong plan usually combines:

  1. Meaningful employer contributions
  2. Fair vesting
  3. Reasonable eligibility rules
  4. Low-cost diversified investments
  5. Reasonable participant fees
  6. Useful default investments
  7. Clear plan information
  8. Appropriate access features

Our detailed 401(k) quality guide provides a checklist.

401(k) Plan Report adds another layer: public filing evidence.

What Form 5500 can tell you about a 401(k)

Most people see only the employee-facing plan portal. Form 5500 provides a plan-level public record.

Depending on the filing, it can show:

401(k) Plan Report turns those filings into comparable employer profiles.

But the public record has limits.

A Form 5500 usually does not tell you the current:

Those require current plan documents.

That distinction is central to the site's methodology.

Have an employer in mind?** Search its retirement plan to see the public filing history, or explore plan benchmarks to understand the range across employers.

A first-paycheck 401(k) checklist

When starting a job, do these things instead of simply accepting the default settings.

Find the match formula

What is the maximum employer contribution, and what do you need to save to receive it?

Check eligibility

Can you contribute immediately? When does the employer contribution begin?

Check vesting

Is employer money immediately yours?

Choose a contribution rate deliberately

Do not confuse the automatic-enrollment default with a recommended savings rate.

Review the default investment

If you were automatically enrolled, confirm where the money is being invested.

Find the fee disclosure

Know what your investments and plan services cost.

Set a beneficiary

Do not leave the beneficiary field for “later.”

Save the SPD

You will be glad you have the plan document when you change jobs years from now.

Frequently asked questions

What is a 401(k) in simple terms?

A 401(k) is a workplace retirement plan that lets employees contribute part of their pay to an investment account with tax advantages. Employers can also contribute.

How does a 401(k) make money?

Your account holds investments selected from the plan's menu. The value can grow through new employee and employer contributions and investment gains, and it can decline through market losses, fees and withdrawals.

Is a 401(k) worth it?

A 401(k) can be highly valuable because of tax advantages, large contribution limits and potential employer contributions. The quality of the specific plan—especially match, fees and investments—still matters.

What is the 401(k) limit for 2026?

The basic employee elective-deferral limit is $24,500. Catch-up contributions can allow more for eligible older participants.

Can I have both a 401(k) and an IRA?

Yes. Many people contribute to both, subject to the applicable contribution and tax rules.

What happens to a 401(k) if I quit?

Your vested balance remains yours. You may be able to keep it in the old plan, roll it to a new plan or IRA, or take a distribution. Unvested employer contributions can be forfeited under the vesting schedule.

Bottom line

A 401(k) is not just a retirement account. It is a piece of your compensation package.

The federal tax rules create the structure, but your employer decides many of the terms that determine how useful the plan is: the match, eligibility, investment menu, fees and optional features.

So learn the basics—but do not stop at the basics.

When you are comparing jobs or trying to understand the plan you already have, look up the employer on 401(k) Plan Report and compare the public filing evidence with the current plan documents.

That is how you move from “my company offers a 401(k)” to understanding what the plan actually looks like.

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Sources and further reading: IRS, 401(k) Plan Overview for Participants ↗ · IRS Topic 424, 401(k) Plans ↗ · U.S. Department of Labor, What You Should Know About Your Retirement Plan ↗

*401(k) Plan Report provides educational information, not individualized investment, tax or legal advice. Plan terms can change; verify current terms in official plan documents.*

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