# What is a 401(k) and how does it work?

> A 401(k) is a retirement account at work. Part of each paycheck goes in automatically, gets invested and earns a tax break.

Source: https://www.walletprep.com/learn/what-is-a-401k/ · Updated 2026-10-04 · Investing

A 401(k) is a retirement account you get through your job. You choose a percentage of each paycheck, your employer sends it into the account before you are paid, and it is invested in funds you pick, with a tax break for saving.

## Key facts
- **It comes from your paycheck.** You set a percentage, like 5%. Each payday that share of your pay goes straight into the account. You never have to move the money yourself.
- **You pick the investments.** Your plan gives you a short menu of funds. You choose one or a few, and your money buys them every payday. If you pick nothing, it goes into the plan's default.
- **It has a tax break.** With a traditional 401(k) you pay less income tax now and pay tax when you take the money out. With a Roth 401(k) you pay tax now and qualified withdrawals later are tax-free.
- **There is a yearly limit.** You can put in up to $24,500 of your pay in 2026. People 50 and over can add $8,000 more. Starting in 2026, if you earned over $150,000 at that job last year, the catch-up must go in as Roth.
- **Your own money stays yours.** Everything you put in, and what it earns, is yours when you leave the job. Money your employer adds may take a few years to become fully yours.

## Where the name comes from
401(k) is the section of the US tax code that created this kind of plan. Only employers can offer one, so you get it through your job. Nonprofits and schools often offer a 403(b), and many government employers offer a 457(b), which work in much the same way.

## How money gets into the account
When you sign up, you choose how much of each paycheck to put in, usually as a percentage. If you earn $2,000 a paycheck and choose 5%, $100 goes into your 401(k) every payday.
Your employer sends it to the plan before the rest lands in your bank account, and it shows as a line on your pay stub. Because you never hold the money, it is easier to keep saving.
Many employers also add money of their own when you contribute, called a match. How a match works, and how to get all of it, is the next lesson.

## What the money is invested in
Money in a 401(k) does not sit as cash. It buys funds, which are baskets that hold many stocks, bonds or both. Your plan offers a menu of maybe 10 to 30 funds, and you choose where your money goes.
A common simple choice is a target-date fund, named for the year you expect to retire. It holds a mix that gets more careful as that year nears. A broad index fund with a low yearly fee is another simple choice.
The value goes up and down with the markets and can fall in some years. Over decades, investing gives your money a chance to grow faster than prices rise.

## The tax break
Most plans offer a traditional 401(k), and many also offer a Roth 401(k). The difference is when you pay income tax.
With traditional, your contribution comes out before income tax is figured, so you pay less tax this year. You pay income tax later, when you take the money out in retirement. With Roth, you pay income tax now, and qualified withdrawals in retirement are tax-free, growth included.
Social Security and Medicare taxes still apply either way. Choosing between the two has its own lesson, and any contribution beats waiting while you decide.

## Getting money out
A 401(k) is meant for retirement. If you take money out before age 59½, you usually pay income tax on it plus a 10% additional tax, with some exceptions.
Some plans allow loans or hardship withdrawals, but both have costs. Treat the account as money you won't touch, and keep an emergency fund for surprises.

## When you leave the job
The money you put in, and anything it has earned, is always 100% yours. Employer money may follow a vesting schedule, which means it becomes yours over a few years of work.
When you leave, you can usually leave the account where it is, or move it to your new employer's plan or an IRA. Cashing out usually means income tax plus the 10% additional tax if you are under 59½.

## A worked example: what $100 a paycheck really costs
Sam earns $52,000 a year, paid $2,000 every two weeks. He puts 5% into a traditional 401(k). His top federal tax rate is 12%.

- 401(k), 5% of $2,000: $100
- Federal tax saved at 12%: −$12
- Drop in take-home pay: = $88
- Paychecks a year: 26
- Into the 401(k) a year: $2,600
- Federal tax saved a year: −$312
- Cost to Sam's take-home: = $2,288

1. Each paycheck, $2,000 × 5% = $100 goes into Sam's 401(k) before federal income tax is figured.
2. That lowers his federal tax by $100 × 12% = $12, so his take-home drops by only $100 − $12 = $88.
3. Over 26 paychecks he saves $100 × 26 = $2,600 and pays $12 × 26 = $312 less federal tax. State tax savings, if any, are extra.

## Common mistakes
- **Never picking any investments.** If you don't choose, your money goes into the plan's default. That may be fine, but check what it is and what it charges.
- **Waiting until you earn more.** Even 1% to 3% of pay starts the habit. You can raise the rate any time, and early dollars have the most years to grow.
- **Cashing out when you change jobs.** A small balance can feel easy to take as cash. Taxes and the 10% additional tax take a big bite, and the money stops growing.

## Questions people ask
### Is a 401(k) worth it if my employer doesn't match?
Usually yes, once your bills are covered and you have a starter emergency fund. You still get the tax break and automatic investing, though high-interest card debt may come first.

### How much should I put in my 401(k)?
Start with at least enough to get any employer match. Many people aim for 10% to 15% of pay over time, counting the match. If that is too much now, start smaller and add 1% a year.

### Can I lose money in a 401(k)?
Yes. The account holds investments, and their value can fall, sometimes sharply. Broad funds have grown over long periods in the past, but that does not promise future results.

### What if my job doesn't offer a 401(k)?
You can open an IRA on your own at a brokerage. It has a lower yearly limit but similar tax breaks, and the IRA lesson explains how it works.

## Do this today
Log in to your benefits portal and find your 401(k). Check three things: your contribution percentage, which fund your money is in, and who your beneficiary is. If you are not enrolled, sign up at 3% or the match level, whichever is higher.

## Sources
- [IRS: 401(k) plan overview](https://www.irs.gov/retirement-plans/plan-participant-employee/401k-resource-guide-plan-participants-401k-plan-overview)
- [IRS: 401(k) plans](https://www.irs.gov/retirement-plans/401k-plans)
- [IRS: Topic 558, additional tax on early distributions](https://www.irs.gov/taxtopics/tc558)
- [IRS: Yearly 401(k) and IRA limit announcement](https://www.irs.gov/newsroom/401k-limit-increases-to-24500-for-2026-ira-limit-increases-to-7500)
- [IRS: Retirement topics, catch-up contributions](https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-catch-up-contributions)
- [IRS: Publication 560, Retirement Plans for Small Business](https://www.irs.gov/publications/p560)

_General education, not personalized financial, tax or legal advice. Figures are examples. Check current rates and limits before you act._