What Is a 401(k)?
A 401(k) is an employer-sponsored retirement plan that allows eligible employees to save money from their paychecks for retirement. The plan is named after Section 401(k) of the Internal Revenue Code.
Instead of receiving all of your wages as take-home pay, you can generally elect to have part of your compensation contributed to your 401(k) through payroll. The money can then be invested using the investment options available in your employer's plan.
A 401(k) is therefore both a retirement savings vehicle and a workplace investing arrangement. The account itself is not a single investment. Your plan may offer mutual funds, index funds, target-date funds, stable value investments or other options.
How Does a 401(k) Work?
A typical 401(k) works through your employer's payroll system. You choose a contribution percentage or dollar amount, subject to plan and IRS limits, and the contribution is deducted from your paycheck.
Enroll in the Plan
If your employer offers a 401(k) and you are eligible, you can enroll according to the plan's rules.
Choose Your Contribution
You decide how much of your paycheck to contribute, subject to the plan's rules and annual IRS limits.
Select Investments
Your contribution is placed into investments selected from the options provided by your employer's plan.
Keep Contributing
Contributions can continue through payroll while you remain eligible and employed under the plan.
Because contributions are automated through payroll, a 401(k) can make retirement saving part of your regular financial routine. Your paycheck is reduced by the amount you contribute, while the contribution is directed into the retirement account.
Traditional 401(k) vs. Roth 401(k)
Employers may offer traditional 401(k) contributions, Roth 401(k) contributions, or both. The main difference is when the contributions receive their tax treatment.
| Feature | Traditional 401(k) | Roth 401(k) |
|---|---|---|
| Contribution type | Generally pre-tax | After-tax |
| Current federal income tax treatment | Contributions generally aren't included in current federal taxable income, subject to applicable rules. | Contributions generally do not reduce current federal taxable income. |
| Taxes on qualified withdrawals | Generally taxable as ordinary income. | Qualified withdrawals are generally tax-free under applicable rules. |
| Availability | Common, but depends on the employer's plan. | Only available if the employer's plan offers the Roth feature. |
Whether traditional or Roth contributions make more sense depends on factors such as your current tax situation, expected future tax situation, income, retirement goals and other accounts.
It is also possible for a plan to allow both types of contributions, subject to applicable annual limits and plan rules.
What Is a 401(k) Employer Match?
Some employers contribute money to an employee's 401(k) when the employee contributes. This is commonly called an employer match.
The matching formula varies by employer. For example, a plan might match a percentage of employee contributions up to a specified percentage of compensation.
Employer contributions are separate from the amount you personally defer from your paycheck. Different annual limits can apply to employee contributions and total contributions to the account.
401(k) Contribution Limits for 2026
The IRS sets annual limits on 401(k) contributions. For 2026, the basic employee elective-deferral limit for most 401(k) plans is $24,500. This limit applies to traditional and Roth employee contributions in the aggregate.
The IRS states that the 2026 basic elective-deferral limit is $24,500. Participants age 50 or older may generally make an additional $8,000 catch-up contribution when permitted by the plan. A higher $11,250 catch-up limit applies for participants ages 60 through 63 under the applicable rules.
The total amount that can be added to a defined-contribution account can be subject to a separate annual limit. For 2026, the IRS lists $72,000 as the general defined-contribution limit, before catch-up contributions.
Contribution limits can change with cost-of-living adjustments, and your employer's plan may impose additional restrictions. Always check current IRS guidance and your plan documents.
How a 401(k) Affects Your Paycheck
A 401(k) contribution can change your take-home pay because money is directed from your paycheck into your retirement account.
With a traditional 401(k), an employee contribution generally reduces the amount of wages subject to current federal income tax. It does not generally avoid Social Security and Medicare taxes on wages.
Roth 401(k) contributions are made with after-tax dollars, so they generally do not reduce current federal taxable income.
Use the Paycheck Tax Calculator to estimate how paycheck deductions can affect take-home pay.
What Can You Invest in With a 401(k)?
Your employer and plan provider determine the investment menu available inside your 401(k). Common options can include:
- Stock mutual funds
- Bond funds
- Broad-market index funds
- Target-date funds
- Stable value funds
- Other investment options specified by the plan
Not every 401(k) offers the same investments. Two employers can have very different investment menus, fees and plan features.
A target-date fund, for example, is designed around an approximate retirement date and generally changes its investment mix over time. A broad-market index fund attempts to track a particular market index.
Investment selection should be considered alongside your time horizon, risk tolerance, diversification needs and the other investments you already own.
Learn more with the Investing for Beginners Guide .
401(k) Fees and Expenses
A 401(k) is not automatically free. Your plan and its investment options can involve different fees and expenses.
Depending on the plan, costs may include:
- Investment expense ratios
- Administrative expenses
- Recordkeeping expenses
- Individual service fees
- Advisory or managed-account fees
Fees can reduce the amount of money that remains invested, so understanding the costs associated with your plan is an important part of evaluating your retirement strategy.
Review your plan's fee disclosures and investment information rather than assuming every 401(k) has the same costs.
What Is 401(k) Vesting?
Vesting determines when you have ownership of certain employer contributions to your retirement account.
Your own contributions are generally yours, while employer contributions can be subject to a vesting schedule under the plan.
For example, an employer may use immediate vesting or a schedule under which employer contributions become fully vested after a specified period.
401(k) Withdrawal Rules
A 401(k) is designed primarily for retirement, so federal rules generally place restrictions on taking money out before retirement.
In general, a distribution taken before age 59½ can be subject to ordinary income tax and an additional 10% tax unless an exception applies. The actual tax treatment depends on the type of contribution, distribution and applicable exception.
Some retirement plans may also allow loans or certain hardship or other permitted distributions. These features are governed by the specific plan and federal rules.
Early access can also have an opportunity cost: money removed from a retirement account is no longer available to potentially grow through investment returns.
Required Minimum Distributions
Traditional retirement accounts can be subject to required minimum distribution (RMD) rules. Under current federal rules, many owners of traditional IRAs and workplace retirement plans must begin taking required distributions at a specified age.
The applicable age and rules depend on factors such as birth year, account type and current law. Some workplace-plan participants may have special rules if they continue working, including rules related to ownership of the employer.
Because RMD rules can change, use current IRS guidance when determining when distributions are required.
What Happens to a 401(k) When You Change Jobs?
Changing employers does not necessarily mean you have to cash out your old 401(k).
Depending on the circumstances and plan rules, possible choices can include:
- Leaving the money in your former employer's plan, if permitted.
- Rolling the balance into your new employer's eligible retirement plan.
- Rolling the balance into an IRA.
- Taking a distribution, subject to applicable tax rules.
A direct rollover can help avoid current taxation that can occur with an improperly handled distribution. The details depend on the type of account, destination account and transaction.
Before moving retirement assets, compare investment choices, fees, services, tax considerations and withdrawal rules.
What Is a 401(k) Rollover?
A rollover generally means moving retirement money from one eligible retirement account or plan to another.
Common situations include moving money from a former employer's 401(k) to a new employer's retirement plan or to an IRA.
There are different rollover methods and tax rules. A direct rollover generally sends the retirement funds directly to the receiving plan or account, while an indirect rollover can involve the participant receiving the money before redepositing it.
Because mistakes can create taxes or penalties, confirm the rollover requirements with the plan administrator and receiving institution before initiating a transaction.
Can You Borrow From a 401(k)?
Some 401(k) plans permit participants to take loans, but a 401(k) loan is not available from every plan.
If a plan allows loans, the plan documents determine the applicable loan amount, repayment period, interest terms and other conditions.
A loan also reduces the amount of money remaining invested while the loan is outstanding. If you leave your employer, the repayment rules can become especially important.
A retirement-plan loan should therefore be considered carefully rather than treated as ordinary spending money.
Potential Advantages of a 401(k)
- Payroll automation: contributions can be deducted automatically from your paycheck.
- Tax advantages: traditional and Roth contributions can provide different tax treatment depending on the account and applicable rules.
- Employer contributions: some employers match employee contributions.
- Retirement-focused investing: the account is designed specifically for long-term retirement savings.
- Investment choices: plans commonly offer multiple investment options.
Potential Limitations of a 401(k)
- Investment choices are limited to the options selected by the plan.
- Withdrawals can be restricted and may result in taxes or penalties.
- Plans can have different fees and administrative costs.
- Employer matching contributions are not available in every plan.
- Employer contributions may have vesting requirements.
- Contribution limits apply.
How Much Should You Contribute to a 401(k)?
There is no contribution percentage that is appropriate for every employee. Your contribution should fit your income, expenses, emergency savings, debt obligations, retirement goals and employer plan.
If your employer offers matching contributions, understand the formula and requirements before deciding how much to contribute.
You can also think about your contribution as a percentage of gross pay rather than only as a dollar amount. This can make it easier to increase contributions when your income rises.
To understand how retirement contributions interact with your paycheck, use the Paycheck Tax Calculator .
Common 401(k) Mistakes to Avoid
Not checking the employer match
If your employer offers matching contributions, make sure you understand how the match works and what requirements apply.
Ignoring investment selections
Contributing money to a 401(k) does not automatically mean you have selected an investment strategy. Check where your money is actually invested.
Ignoring fees
Compare the costs of available investment options and understand the administrative fees charged by the plan.
Forgetting about old accounts
If you change jobs, review what happens to your previous 401(k) instead of automatically taking a cash distribution.
Contributing beyond the applicable limit
Keep track of your employee contributions, especially if you participate in more than one employer plan during the year.
Treating retirement savings as emergency cash
Early withdrawals can have tax consequences and can reduce the money available for future retirement needs.
401(k) for Beginners: A Simple Checklist
If you are enrolling in a 401(k) for the first time, you can use this checklist to organize the basics:
- Confirm whether your employer offers a 401(k).
- Check when you become eligible to participate.
- Review the employer matching formula, if any.
- Choose between available traditional and Roth contribution options.
- Set a contribution amount that fits your budget.
- Review the investment options offered by the plan.
- Check investment and account fees.
- Understand the vesting schedule for employer contributions.
- Review your contribution periodically.
- Revisit your account when you change jobs or your financial situation changes.
401(k) Frequently Asked Questions
What is a 401(k)?
A 401(k) is an employer-sponsored retirement plan that lets eligible employees contribute part of their pay to a retirement account and invest the money using the options offered by the plan.
How does a 401(k) work?
You generally choose how much of your paycheck to contribute. The contribution is processed through payroll and the money can be invested according to your selections from the plan's available investment options.
What is the 401(k) contribution limit for 2026?
The basic employee elective-deferral limit for most 401(k) plans is $24,500 in 2026. Eligible participants may also have catch-up contribution opportunities subject to age, plan and IRS rules.
What is the difference between a traditional 401(k) and a Roth 401(k)?
Traditional 401(k) contributions generally receive tax treatment before retirement, with taxes generally due on withdrawals. Roth 401(k) contributions are made with after-tax dollars, and qualified Roth withdrawals can generally be tax-free under applicable rules.
Does an employer have to match 401(k) contributions?
No. Employer matching contributions depend on the employer's plan. Some employers match a portion of employee contributions according to a specified formula and limit.
Can I withdraw money from my 401(k) before retirement?
Some plans permit certain withdrawals or loans, but early access can result in income taxes and potentially an additional tax unless an exception applies.
What happens to my 401(k) when I change jobs?
Depending on the plan and circumstances, you may be able to leave the money in the old plan, roll it into another eligible retirement plan or IRA, or take a distribution subject to applicable rules.
Is a 401(k) an investment?
No. A 401(k) is a retirement plan or account. The money inside the account can be invested in the investments made available by your employer's plan.