How a 401(k) Works: The Basics of Employer Retirement Savings

A 401(k) is a retirement savings account your employer offers

A 401(k) is a retirement savings plan that your employer sets up and you contribute to through payroll deductions. Money comes out of your paycheck before taxes are calculated, which lowers your taxable income for the year. Your employer may match a portion of what you contribute — for example, matching 50 cents for every dollar you put in, up to a certain percentage of your salary. The money you contribute grows tax-free until you withdraw it in retirement, usually after age 59½.

The name comes from the section of the tax code that created it. Not all employers offer a 401(k); some offer similar plans like a 403(b) for nonprofits or a 457 plan for government workers. If your employer does offer one, you decide how much of each paycheck to contribute, and you choose how that money is invested from a list of options your plan provides.

Key Takeaways

• Money you contribute to a 401(k) comes directly from your paycheck before income tax is taken out, reducing what you owe in taxes that year.
• Your employer may match part of your contribution, which is information programs added to your account as long as you contribute enough to receive it.
• You choose how your 401(k) money is invested from a menu of funds provided by your plan, typically stocks, bonds, and target-date funds.
• You cannot withdraw money before age 59½ without penalty, except in rare hardship situations or if you leave your job.
• When you leave your job, you can roll your 401(k) into an IRA or your new employer's plan to keep it growing tax-free.

How contributions and employer matching work

You decide what percentage of your paycheck goes into your 401(k) — typically between 1% and 50% of your gross salary, though your plan may set its own limits. That amount is deducted before federal income tax is calculated, so if you earn $50,000 and contribute $5,000 to your 401(k), you only pay income tax on $45,000. This is called a pre-tax contribution, and it reduces your tax bill for the year.

Many employers offer a match, which means they add money to your account based on how much you contribute. A common match is 100% of the first 3% you contribute, or 50% of the first 6%. If your employer matches 100% of the first 3% and you contribute 3% of a $50,000 salary ($1,500), your employer adds another $1,500. If you contribute only 2%, they add only $1,000. Not all employers match, and those that do set their own terms — there is no standard amount.

The match is when ready information programs, so most financial advisors recommend contributing at least enough to get the full match. After you reach the match limit, you can choose to contribute more if you want to save additional money for retirement.

Investment options and how your money grows

Your 401(k) plan offers a menu of investment funds — usually 10 to 30 options. Common choices include stock funds (which tend to grow faster but fluctuate more), bond funds (which are more stable but grow slower), and target-date funds (which automatically shift from stocks to bonds as you approach retirement). You decide how to split your contributions among these options, and you can change your allocation at any time.

The money you invest grows tax-free while it sits in the account. If a stock fund in your 401(k) gains $2,000 in value, you do not pay tax on that $2,000 that year. You only pay tax when you withdraw the money in retirement. This tax-free growth is one of the biggest advantages of a 401(k) — your money compounds faster than it would in a regular savings account.

If you are unsure which funds to pick, many plans offer a default option, often a target-date fund based on when you expect to retire. You can also ask your plan administrator for educational materials or speak with a financial advisor.

Contribution limits and annual maximums

The IRS sets a maximum amount you can contribute to a 401(k) each year. This limit changes annually and is higher if you are age 50 or older. For example, in 2024 the limit was $23,500 for workers under 50 and $31,000 for workers 50 and older, but these amounts increase most years. Your employer will tell you the current limit, and your plan will not let you contribute more than the IRS allows.

The employer match does not count toward your personal contribution limit — it is separate. So if you hit the IRS limit, your employer can still add their match on top of it. However, the total of your contributions plus the employer match cannot exceed a different, higher limit set by the IRS each year.

Withdrawals and the 59½ rule

You cannot withdraw money from your 401(k) before age 59½ without paying a 10% early withdrawal penalty on top of regular income tax. If you withdraw $10,000 at age 45, you owe the 10% penalty ($1,000) plus income tax on the full $10,000. This is why a 401(k) is meant for long-term retirement savings, not emergency money.

There are narrow exceptions: you can withdraw without penalty if you leave your job after age 55, if you have a serious financial hardship (defined by the IRS), or if you are disabled. Some plans also allow loans — you borrow from your own 401(k) and repay yourself with interest. Loans do not trigger the penalty, but if you leave your job before repaying, the loan balance is treated as a withdrawal and taxed.

Once you reach age 59½, you can withdraw as much as you want whenever you want. You will owe income tax on the withdrawal, but no penalty. At age 73, the IRS requires you to begin taking required minimum distributions (RMDs) — a set amount each year based on your age and account balance.

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

When you leave your job, your 401(k) stays in that employer's plan unless you move it. You have several options: leave it where it is, roll it into your new employer's 401(k) if they offer one, or roll it into an Individual Retirement Account (IRA). A rollover means moving the money directly from one account to another without you touching it, so no tax is owed and no penalty applies.

Many people roll their old 401(k) into an IRA because IRAs often offer more investment choices and lower fees. To do a rollover, you contact the new financial institution (the IRA provider), and they handle the transfer directly from your old plan. The money continues to grow tax-free in the new account.

If you withdraw the money yourself instead of doing a rollover, you owe income tax on the full amount and a 10% penalty if you are under 59½. For example, if you cash out a $50,000 401(k) at age 40, you might owe $15,000 or more in taxes and penalties, leaving you with only $35,000. This is why a direct rollover is almost always the better choice.

Pre-tax versus Roth contributions

Most 401(k)s offer pre-tax contributions, which lower your taxes now but you pay tax on withdrawals in retirement. Some employers also offer Roth 401(k) contributions, where you pay tax on the money now but withdrawals in retirement are tax-free. You choose which type to use, and some plans let you split your contributions between both.

Pre-tax is better if you expect to be in a lower tax bracket in retirement or if you want to reduce your taxes this year. Roth is better if you expect to be in a higher tax bracket in retirement or if you want to avoid taxes on growth. There is no universal right answer — it depends on your situation and what you expect your income to be in retirement.

Fees and how they affect your balance

401(k) plans charge fees, which come out of your account balance. Common fees include an administrative fee (charged by the employer to run the plan), investment fees (charged by the fund companies for managing the funds), and advisory fees (if you use a financial advisor through the plan). These fees vary widely — some plans charge less than 0.5% per year, while others charge 1% or more.

Over decades, even small fee differences add up. A 1% annual fee on a $100,000 balance costs $1,000 per year. Your plan statement should show you what fees you are paying. If your plan's fees seem high, ask your employer if they offer lower-cost options or if they are considering switching providers.

Frequently Asked Questions

Can I contribute to a 401(k) and an IRA at the same time?

Yes, you can contribute to both. However, if you contribute to a traditional IRA, you may not be able to deduct those contributions on your taxes if you also have a 401(k) at work, depending on your income. A Roth IRA has no such restriction. Check with a tax professional about your specific situation.

What happens to my 401(k) if I am laid off?

Your 401(k) belongs to you, not your employer. If you are laid off, the money stays in your account. You can leave it there, roll it to an IRA, or roll it to your new employer's plan. You cannot withdraw it penalty-free unless you are age 55 or older, or meet another exception.

Can I borrow from my 401(k)?

Many plans allow loans, typically up to 50% of your balance or $50,000, whichever is less. You repay the loan with interest, usually over five years. If you leave your job before repaying, the loan balance is treated as a withdrawal and taxed. Loans should be a last resort because they reduce the money growing for retirement.

What if my employer does not offer a 401(k)?

You can open an Individual Retirement Account (IRA) on your own through a bank or brokerage. IRAs have lower contribution limits than 401(k)s, but they offer more investment choices. Some self-employed people or small business owners can set up a Solo 401(k) or SEP IRA instead.

Do I have to invest in stocks, or can I choose safer options?

You choose. Most plans offer bond funds and stable value funds that are less risky than stock funds. Target-date funds automatically become more conservative as you age. However, historically stocks have provided better long-term growth, so many financial advisors recommend holding some stock exposure even in retirement.