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

Pamela Rodriguez, CFP® · 2023-07-17

Updated 2026-11-10

By Pamela Rodriguez, CFP® · Last updated November 10, 2026

Quick answer: A 401(k) is a retirement plan you get through work. You choose a percentage of your paycheck, it goes into your account automatically, and you invest it in the plan's options. Depending on your plan, you can save pre-tax or Roth, and your employer may add a match.

401(k)s can be confusing. Maybe you're starting a new job. Maybe you just left one and have no idea what to do with the old account. Or maybe a rollover check landed in your mailbox and now you're afraid to touch it.

I'll keep this simple. By the end, you'll know how a 401(k) works, how much you can contribute, what the match and vesting mean, how withdrawals are taxed, and what to do when you leave your job.

How does a 401(k) work?

A 401(k) is an employer-sponsored, defined contribution retirement plan. The name comes from section 401(k) of the tax code, which is why it sounds so exciting.

Here's how it works:

1. You enroll, or your employer enrolls you. Many plans use automatic enrollment, so you may see a deduction without signing up yourself.
2. You pick a contribution rate. Your plan takes that amount from each paycheck.
3. You choose your investments. Most plans offer a menu of funds, often including a target date fund.
4. Your employer may contribute. That can be a match or another employer contribution.
5. Your money grows inside the plan. You don't pay tax each year on investment growth inside the account.
6. You use it in retirement. Taxes then depend on whether the money is pre-tax or Roth.

If you're surprised by a new payroll deduction, ask HR whether your plan has automatic enrollment. Requirements and exceptions depend on the plan and employer. You can generally change the election or opt out; confirm the process and effective date with the administrator. Review the IRS overview of 401(k) plans and your plan documents.

Here's the catch: a 401(k) can give you an account, but it can't tell you what to do next. That's why Golden Wealth Capital built ORO, so your next money move doesn't have to be a guess.

Traditional vs. Roth 401(k): which is better?

The main difference is when you pay taxes. A traditional 401(k) lowers your taxable income today, while a qualified Roth withdrawal can be tax-free later.

Here's a simple example. You earn $450,000, get paid 24 times a year, and contribute the 2026 maximum of $24,500. To keep the math easy, I'm using a flat 35% tax and ignoring payroll and state taxes.

The Roth costs about $357 more per paycheck today, or $8,575 over the year. In exchange, qualified withdrawals can be tax-free later. At this income, your plan's nondiscrimination testing could also limit how much you can contribute, so check with HR.

Nobody knows what taxes will look like in 30 years, so this isn't one size fits all. Your income, age, family, and other savings all matter. Many people also split contributions between the two if their plan allows it.

Not every plan offers a Roth option, so check with HR. Employer matching may be pre-tax even when your contributions are Roth. Some plans permit designated Roth matching contributions, subject to eligibility, vesting, election, and tax-reporting rules. Confirm what your plan offers.

401(k) contribution limits for 2026

For 2026, the standard employee deferral limit is $24,500, subject to compensation and plan restrictions. The limit applies to your traditional and Roth contributions combined.

Eligible catch-up participants can have a combined employee deferral limit of $32,500, or $35,750 for the age-60-through-63 group, if the plan permits it. For a later tax year, use the IRS's announced limits rather than a projection.

A rule for higher earners: The 2026 Roth catch-up requirement generally affects participants whose prior-year wages with the plan sponsor exceeded $150,000. Confirm your eligibility, Roth availability, and the plan's implementation with the administrator.

How much should you contribute?

Start by contributing enough to get your full employer match. That's part of your pay package, so I hate seeing it left on the table.

After that, it depends on your debt, emergency savings, retirement timeline, and goals. A percentage alone cannot tell you whether you are on track. Choose an affordable starting point and review increases as income or obligations change.

How does a 401(k) match work?

A match is money your employer adds based on what you contribute. It doesn't count against your personal $24,500 limit, but it does count toward the overall limit.

Common formulas include:

• 100% of the first 3% you contribute
• 100% of the first 3%, plus 50% of the next 2%
• 100% of the first 6% you contribute

Two things to ask HR:

• Do you offer a true-up? If you hit the limit early in the year, a true-up can prevent you from missing part of the match.
• Do you match qualified student loan payments? Ask whether your employer offers this optional feature and what certification is required. Do not assume it is included in every plan.

What is 401(k) vesting?

Vesting decides how much of your employer's money you keep if you leave. Your own contributions are always 100% yours.

There are three common setups:

• Immediate: The employer money is yours right away.
• Cliff: You own none of it until a set date, then all of it.
• Graded: You own a little more each year.

A six-year graded schedule might look like this:

If you leave after four years with $10,000 of employer money, you would keep 60%, or $6,000. Before you give notice, check your vesting schedule. Sometimes waiting a few weeks makes a real difference.

When can you withdraw money from a 401(k)?

You can generally withdraw without the 10% early withdrawal tax starting at age 59½, but regular income tax may still apply. Before then, the rules depend on your plan and why you need the money. Many plans limit withdrawals while you still work there, even if you have a balance.

A Roth withdrawal is generally qualified after you've had the Roth account for five years and you've reached 59½, become disabled, or died.

The IRS lists exceptions to the 10% additional tax, each with its own conditions. One is separation from service during or after the year you turn 55, for qualifying distributions from that employer's plan. That exception does not apply to IRA distributions. Confirm the separation date, plan, and withdrawal rules before acting. An exception to the additional tax does not necessarily remove regular income tax.

Required minimum distributions depend on your birth year, account type, employment, ownership, and applicable rules. Some employer plans allow an eligible still-working participant to delay them. Designated Roth 401(k) accounts do not require lifetime RMDs for the owner under current rules. Beneficiary rules differ.

What happens to your 401(k) when you leave your job?

Your vested money stays yours. You usually have four options, and a rollover isn't automatically the right one.

Don't assume you can ignore a small balance. Your plan may have an involuntary distribution or automatic-rollover provision. Read the administrator's notice, confirm the current threshold and your options, and respond before the deadline instead of relying on a figure from an older article.

If you cash out, the plan generally must withhold 20% for federal income tax. That may not cover everything you owe, especially if the 10% additional tax also applies.

How to roll over a 401(k)

A direct rollover is usually the cleanest way to do this. The money goes straight to your new plan or IRA, and the mandatory 20% withholding doesn't apply.

1. Decide where the money should go, and compare fees and investments first.
2. Open the new IRA if you need one, or get your new plan's rollover instructions.
3. Call your old plan and ask for a direct rollover. If they mail a check, it should be payable to the new account, not to you.
4. Forward the check if needed, and confirm that it posted.
5. Invest the money. Rolled money can sit in cash until you choose investments.

If the check is paid to you, you generally have 60 days to complete the rollover. Because 20% was withheld, you'd need to replace that amount from other money to roll over the full balance.

New 401(k) rules to know

• Part-time workers: Ask your administrator to check your credited service and eligibility under the current long-term part-time rules. Eligibility for employee deferrals does not necessarily establish eligibility for an employer contribution.
• Saver's Match: Check the IRS explanation of the Saver's Match for the program beginning in tax year 2027. Eligibility, qualifying contributions, and account requirements matter; it is not an automatic benefit for every saver.

401(k) questions I hear all the time

Are 401(k)s a scam?

No. People usually say this after high fees, a bad investment choice, or selling during a market drop. Those are real problems, but they don't make the account itself a scam.

Is a 401(k) worth it without a match?

Often, yes. You still get payroll automation and tax benefits, plus higher contribution limits than an IRA. It may be less attractive if the investment choices are poor or fees are high, so compare it with an IRA.

What happens to my 401(k) loan if I quit?

Check your plan's rules right away. Unpaid loans can be treated as distributions, which may mean taxes and possibly the 10% additional tax. If your loan balance is offset from your account after you leave, you may have until your tax filing deadline, including extensions, to roll over that amount.

I got a check I never requested. What do I do?

Don't cash it until you understand it. It may be a small balance your old plan was allowed to pay out, and cashing it can create a tax bill. If it's a rollover-eligible payment, the 60-day clock generally starts when you receive it.

How do I find an old 401(k)?

Start with your old employer's HR department or your old statements. Then ask for the plan's current administrator.

Your 401(k) shouldn't leave you guessing

Most people get a login, a list of funds, and a phone number. Then they're on their own with the questions that matter most: how much to save, what to pay off first, and what to do with an old account.

Learn about ORO as part of Golden Wealth Capital's approach to financial decisions. Confirm available features and data coverage before relying on any app display. It is not a substitute for your plan's official records or qualified advice.

If you're an employee, don't wait for your next statement

A few 401(k) decisions have real deadlines:

• Your annual limit doesn't wait. Contribution room for 2026 ends with the year, and you can't go back and make up what you missed.
• Your vesting date matters. Leaving a few weeks too early could cost you employer money.
• Your rollover clock may already be running. If a check was paid to you, you generally have 60 days.
• Your new job may have a short enrollment window. Ask now, so you don't miss the match.

Don't let one of these decide for you. Talk with our team about your 401(k) before your next deadline passes.

If you're an employer, your team is already asking

Your employees have money questions, whether they bring them to you or not. The real question is who's helping them answer.

Employers can discuss workplace retirement needs with Golden Wealth Capital. Confirm the scope, availability, responsibilities, and fees of any proposed service in a written agreement rather than assuming a particular plan or ORO feature is included.

A new plan year is right around the corner. Now is the time to find out where your plan stands, before another year goes by on autopilot.

Ask about a 401(k) plan review and confirm what information and analysis would be included.

This article is for educational purposes and isn't personalized investment, tax, or legal advice. Plan rules vary, so check your plan documents and speak with a qualified professional about your situation. Golden Wealth Capital may earn fees if you roll assets into an account we manage, which creates a conflict of interest. ORO provides educational context and does not make trades. Limits and rules can change.