How Does a 401(k) Work? 2026 Limits, Matching and Rules

If your employer offers a 401(k), it is often the simplest and most powerful retirement tool you have. Money comes straight out of your paycheck, it grows without yearly taxes on dividends or gains, and many employers add free money on top through a match. Yet plenty of workers never enroll, contribute too little to get the full match, or cash out when they change jobs.

This guide explains how a 401(k) works in plain English: the official 2026 contribution limits, how employer matching and vesting work, traditional vs. Roth 401(k) contributions, and the rules for loans, withdrawals and rollovers.

Key takeaways

• A 401(k) is an employer-sponsored retirement plan funded through automatic payroll deductions.
• For 2026 you can defer up to $24,500 of your salary, plus an $8,000 catch-up if you are 50 or older ($11,250 instead if you are 60 to 63), according to the IRS.
• Your own contributions are always yours; employer contributions may follow a vesting schedule.
• Withdrawals before age 59½ usually face income tax plus a 10% additional tax, with some exceptions.
• When you leave a job, a direct rollover keeps your savings tax-deferred.

What is a 401(k)?

A 401(k) is a defined contribution retirement plan named after the section of the US Internal Revenue Code that created it. Your employer sets up the plan and picks a menu of investments, usually mutual funds, index funds and target-date funds. You decide what percentage of each paycheck to contribute and how to invest it.

The SEC’s Investor.gov describes the core advantage: contributions to a traditional 401(k) are made with pre-tax dollars, and taxes on the money and its earnings are deferred until you withdraw it.

How a 401(k) works, step by step

1. You enroll. Many plans now enroll new hires automatically at a default rate; you can usually change the rate or opt out.
2. You choose a contribution rate. For example, 6% of each paycheck. The money is taken out before it reaches your bank account.
3. Your employer may add money. This can be a matching contribution, a profit-sharing contribution, or both.
4. You choose investments. If you do nothing, your money typically goes into the plan’s default fund, often a target-date fund.
5. The account grows tax-advantaged. You don’t pay tax each year on interest, dividends or gains inside the account.
6. You withdraw in retirement. Traditional money is taxed as ordinary income when withdrawn; qualified Roth withdrawals are tax-free.

2026 401(k) contribution limits

The IRS adjusts limits for inflation each year. These are the official figures for 2026 from IRS Notice 2025-67 and the IRS cost-of-living adjustments page:

So in 2026 a worker aged 50 to 59 or 64+ can defer up to $32,500, and a worker aged 60 to 63 can defer up to $35,750. The employee deferral limit is shared across all 401(k) and 403(b) plans you participate in during the year, so if you switch jobs mid-year, keep track of what you already contributed. The 2027 limits have not been announced yet; the IRS usually publishes them in late October or November.

New rule for high earners: starting in 2026, if your prior-year FICA wages from the employer sponsoring the plan exceeded $150,000, any catch-up contributions you make must go in as Roth (after-tax) contributions. The IRS summarizes this on its catch-up contributions page.

Employer matching: the “free money” part

Many employers match part of what you contribute. Matching formulas vary, and your plan’s Summary Plan Description spells out the exact terms. Two common examples:

• 100% match up to 3% of pay: if you earn $60,000 and contribute 3% ($1,800), your employer adds $1,800.
• 50% match up to 6% of pay: on the same salary, contributing 6% ($3,600) earns a $1,800 match.

In both cases, contributing less than the threshold leaves part of the match unclaimed. A common rule of thumb is to contribute at least enough to capture the full match before putting extra money toward other goals, but whether that fits you depends on your budget, debts and emergency savings. If you don’t yet have a cash cushion, our guide to high-yield savings accounts covers where to keep it.

Vesting: when employer money becomes yours

Your own salary deferrals are always 100% vested. Employer contributions, however, can be subject to a vesting schedule. According to the IRS, 401(k) plans can use immediate vesting, “cliff” vesting where you become 100% vested after up to 3 years of service, or “graded” vesting that increases each year until you are fully vested after 6 years. If you leave before you are fully vested, you may forfeit the unvested portion of employer contributions, so it is worth checking your vesting status before changing jobs.

Traditional vs. Roth 401(k) contributions

Many plans let you choose between two tax treatments, or split your contributions between them:

• Traditional (pre-tax): contributions reduce your taxable income now. Withdrawals in retirement, including earnings, are taxed as ordinary income.
• Roth (after-tax): no tax break now, but qualified withdrawals of contributions and earnings are tax-free. Generally a withdrawal is qualified if you are at least 59½ (or disabled, or it is paid after your death) and it has been at least five years since your first Roth contribution to the plan.

The decision mostly comes down to whether you expect your tax rate to be higher now or in retirement. Unlike a Roth IRA, a Roth 401(k) has no income limit for contributing. The trade-offs are very similar to the ones we cover in Roth IRA vs. traditional IRA, and you can contribute to both a 401(k) and an IRA in the same year, although your workplace plan coverage can affect whether a traditional IRA contribution is deductible.

Choosing your 401(k) investments

Your plan offers a limited menu, which is actually helpful for beginners. Common options include:

• Target-date funds: a single fund that holds a mix of stocks and bonds and gradually becomes more conservative as its target year approaches.
• Index funds: low-cost funds that track a broad market index such as the S&P 500 or a total bond market index.
• Stable value or money market funds: lower-risk options with lower expected long-term returns.

Fees matter because they are deducted every year and compound over decades. Your plan must give you fee disclosures; look for each fund’s expense ratio and any administrative fees. The US Department of Labor’s guide to 401(k) plan fees explains what to look for. All investments carry risk, including loss of principal, and past performance doesn’t guarantee future results.

401(k) loans and hardship withdrawals

Plans are allowed, but not required, to offer loans. Under the IRS loan rules, the maximum loan is generally the lesser of $50,000 or the greater of $10,000 or 50% of your vested balance. Loans must usually be repaid within five years through regular payments that include interest (longer terms may be allowed for buying a primary home). If you don’t repay as required, the outstanding balance can be treated as a taxable distribution and may also trigger the 10% additional tax.

Some plans also allow hardship distributions for an immediate and heavy financial need. Unlike a loan, a hardship withdrawal isn’t paid back, is generally taxable, and may be subject to the early withdrawal tax. Both options reduce the money that stays invested for retirement, so treat them as a last resort.

Withdrawing from a 401(k)

Early withdrawals

Money taken out before age 59½ is generally subject to income tax plus a 10% additional tax. The IRS lists the exceptions, which include:

• Leaving your employer during or after the year you turn 55 (the so-called “rule of 55”), for money in that employer’s plan.
• Total and permanent disability, or certification of a terminal illness.
• One emergency personal expense distribution per year of up to $1,000.
• Up to $5,000 per child for qualified birth or adoption expenses.

Note that some well-known IRA exceptions, such as the first-time homebuyer and higher education exceptions, do not apply to 401(k) plans. See also IRS Topic 558.

Required minimum distributions

You can’t leave pre-tax money in a 401(k) forever. Required minimum distributions (RMDs) generally must begin at age 73, although if you are still working and don’t own 5% or more of the company, many plans let you delay RMDs from that employer’s plan until you retire. Since 2024, designated Roth accounts in 401(k) plans are no longer subject to RMDs while the account owner is alive. Details are in the IRS RMD FAQs.

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

Your vested balance stays yours. You typically have four options:

1. Leave it in your old plan, if the plan allows it.
2. Roll it into your new employer’s plan, if that plan accepts rollovers.
3. Roll it into an IRA, which often gives you a wider choice of investments.
4. Cash it out, which usually means income tax, possibly the 10% additional tax, and lost tax-deferred growth.

A direct rollover (trustee to trustee) is usually the cleanest choice. If the plan pays the money to you instead, it generally must withhold 20% for federal tax, and you have 60 days to deposit the full amount, including the withheld 20% from other funds, to avoid tax on the difference. The IRS explains the details on its rollovers page.

Common 401(k) mistakes to avoid

• Not contributing enough to get the full match.
• Never raising your contribution rate. Many plans offer automatic annual increases; raising your rate when you get a pay rise is painless.
• Ignoring fees. Compare expense ratios when choosing between similar funds.
• Cashing out when changing jobs.

If you have a high-deductible health plan, a health savings account can complement your 401(k) as another tax-advantaged way to save. Lower-income savers may also qualify for the Saver’s Credit for 401(k) contributions.

Frequently asked questions

How much can I contribute to a 401(k) in 2026?

Up to $24,500 in employee deferrals. If you are 50 or older you can add an $8,000 catch-up, or $11,250 if you are 60 to 63. Total contributions from you and your employer can’t exceed $72,000 (not counting catch-ups) or 100% of your compensation, if less.

Does an employer match count toward my $24,500 limit?

No. The $24,500 limit applies to your own elective deferrals. Employer contributions count toward the separate overall limit of $72,000 for 2026.

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

Yes. The limits are separate. However, being covered by a workplace plan may reduce or eliminate the deduction for traditional IRA contributions above certain income levels, and Roth IRA eligibility has its own income limits.

Is a 401(k) worth it if my employer doesn’t match?

It can still be worthwhile because of the tax advantages and automatic saving, but it depends on the plan’s investment options and fees and on your other goals. Compare it with an IRA before deciding.

The bottom line

A 401(k) works best when you start early, contribute at least enough to collect any employer match, keep fees low and leave the money invested until retirement. Review your contribution rate once a year, check your vesting status before changing jobs, and use a direct rollover to avoid unnecessary taxes.

Disclaimer: This article is for general educational purposes only and is not financial, tax or legal advice. Rules and limits can change, and your plan’s terms may differ. Check official IRS sources and your plan documents, or consult a qualified professional, before making decisions.