A 401(k) is the most widely used retirement savings account in the United States. If your employer offers one, it’s almost always worth participating — especially if there’s a matching contribution. Yet millions of workers either don’t enroll or don’t understand how the account works.
This guide explains everything: how a 401(k) works, contribution limits for 2026, employer match rules, investment options, and what to do with your account when you change jobs.
What Is a 401(k)?
A 401(k) is an employer-sponsored retirement savings plan governed by the IRS. You contribute a portion of your paycheck directly into the account before taxes are taken out (for traditional 401(k)s) or after taxes (for Roth 401(k)s). The money grows tax-advantaged until retirement.
The name comes from the section of the Internal Revenue Code that authorizes it: Section 401(k).
Traditional 401(k) vs. Roth 401(k)
| Feature | Traditional 401(k) | Roth 401(k) |
|---|---|---|
| Contributions | Pre-tax (lowers taxable income now) | After-tax (no immediate tax break) |
| Growth | Tax-deferred | Tax-free |
| Withdrawals in retirement | Taxed as ordinary income | Tax-free (if rules are met) |
| Best for | Higher earners now who expect lower income in retirement | Lower earners now who expect higher income in retirement |
Many employers now offer both options. If you’re early in your career and expect your income to grow, the Roth 401(k) is often the better long-term choice.
2026 401(k) Contribution Limits
| Type | 2026 Limit |
|---|---|
| Employee contribution limit (under 50) | $23,500 |
| Catch-up contribution (age 50–59, 64+) | Additional $7,500 ($31,000 total) |
| Super catch-up (age 60–63, per SECURE 2.0) | Additional $11,250 ($34,750 total) |
| Total limit including employer contributions | $70,000 |
The IRS adjusts these limits annually for inflation. Contributing up to the limit each year is one of the most powerful wealth-building moves available to working Americans.
How Employer Matching Works
Many employers match a portion of your contributions — free money added to your retirement account. Common structures include:
- 100% match up to 3% of salary: If you earn $60,000 and contribute $1,800 (3%), your employer adds $1,800.
- 50% match up to 6% of salary: If you earn $60,000 and contribute $3,600 (6%), your employer adds $1,800.
- Tiered matching: Some employers use a graduated formula based on contribution percentage.
Always contribute at least enough to capture the full employer match. Failing to do so is leaving part of your compensation on the table.
Vesting Schedules
Your own contributions are always yours immediately. Employer contributions may be subject to a vesting schedule — meaning you must stay with the company for a certain number of years before that money is fully yours.
- Cliff vesting: You own 0% until year 3, then 100%.
- Graded vesting: You own an increasing percentage each year (e.g., 20% per year over 5 years).
Where Does the Money Get Invested?
Your employer’s 401(k) plan offers a menu of investment options, typically including:
- Index funds (S&P 500, total market)
- Target-date funds (automatically shift to conservative as you age)
- Bond funds
- Actively managed stock funds
- Sometimes company stock
For most people, a low-cost index fund or a target-date fund matching your expected retirement year is the best default choice. Target-date funds (e.g., “Target 2050 Fund”) automatically rebalance as you approach retirement.
When Can You Withdraw from a 401(k)?
Normal withdrawals
You can withdraw from a traditional 401(k) starting at age 59½ without penalty. Withdrawals are taxed as ordinary income. Required minimum distributions (RMDs) begin at age 73.
Early withdrawals
Withdrawing before age 59½ results in a 10% penalty plus income tax on the amount. Exceptions include:
- Permanent disability
- Separation from service at age 55 or older
- Substantially equal periodic payments (Rule 72(t))
- Hardship distributions (specific qualifying reasons)
Loans
Many plans allow you to borrow from your 401(k) — up to 50% of your vested balance or $50,000, whichever is less. You repay yourself with interest. The risk: if you leave your job, the loan may become due immediately.
What Happens to Your 401(k) When You Leave a Job?
You have four options:
- Leave it with your former employer — only practical if the plan has good investment options and low fees.
- Roll it into your new employer’s 401(k) — simplifies tracking and may access better options.
- Roll it into an IRA — often the most flexible and lowest-cost option, with broader investment choices.
- Cash it out — triggers taxes and a 10% penalty if under 59½. Avoid this option in almost all cases.
The direct rollover (where funds move directly from plan to plan without passing through your hands) avoids any tax withholding. Always request a direct rollover.
How Much Should You Contribute?
Start by contributing enough to capture the full employer match — that’s a guaranteed 50%–100% return on that portion. Beyond that, the standard guidance is to save at least 10%–15% of your income for retirement. If you’re starting late, aim higher.
Even small increases matter. Going from 6% to 8% of a $50,000 salary adds $1,000 per year to your retirement account — and that money compounds over decades.
Bottom Line
A 401(k) is the cornerstone of retirement savings for most working Americans. Contribute at least enough to get the full employer match, choose low-cost index funds, and leave the money invested for the long term. The tax advantages and employer contributions make it one of the highest-return financial moves available to you regardless of income level.