What is a 401(k) and How Does It Work?
A 401(k) is an employer-sponsored retirement savings plan that lets you invest pre-tax dollars directly from your paycheck. The money grows tax-deferred — meaning you pay no income tax on contributions or investment gains until you withdraw in retirement. This makes it one of the most powerful wealth-building tools available to American workers.
In 2026, the IRS allows employees to contribute up to $23,500 per year (up from $23,000 in 2024). Workers aged 50 or older can contribute an additional $7,500 "catch-up" contribution, bringing the total to $31,000. These limits apply to your contributions only — employer match does not count toward this limit.
How Employer Match Works — Free Money You Should Never Leave Behind
Most employers match a percentage of your contributions up to a certain limit. The most common structure is "100% match on the first 3–6% of salary." If your employer matches 100% on the first 5% and you earn $75,000, contributing 5% ($3,750) gets you another $3,750 from your employer — a 100% instant return on that money before any market gains.
Not contributing enough to get the full match is the single most expensive financial mistake American workers make. At $75,000 salary with a 5% match, failing to contribute 5% costs you $3,750 per year — or approximately $450,000 in lost wealth over 30 years at 7% returns.
401(k) vs Roth 401(k) — Which is Better?
| Feature | Traditional 401(k) | Roth 401(k) |
|---|
| Contributions | Pre-tax (reduces taxable income now) | After-tax (no deduction now) |
| Growth | Tax-deferred | Tax-free |
| Withdrawals in retirement | Taxed as ordinary income | Tax-free |
| Required Minimum Distributions | Yes, starting at age 73 | No RMDs (starting 2024) |
| Best for | High income now, lower in retirement | Lower income now, higher in retirement |
General rule: choose Traditional 401(k) if you expect to be in a lower tax bracket in retirement. Choose Roth 401(k) if you expect to be in the same or higher bracket, or if you are early in your career.
401(k) Contribution Strategy — What the Numbers Say
| Salary | 5% Contribution | 10% Contribution | Max ($23,500) | Balance at 65 (7%) |
|---|
| $50,000 | $2,500/yr | $5,000/yr | $23,500/yr | $1.04M (at max) |
| $75,000 | $3,750/yr | $7,500/yr | $23,500/yr | $1.04M (at max) |
| $100,000 | $5,000/yr | $10,000/yr | $23,500/yr | $1.04M (at max) |
| $150,000 | $7,500/yr | $15,000/yr | $23,500/yr | $1.04M (at max) |
The 4% Rule — Converting Your Balance to Monthly Income
The 4% Rule states that you can withdraw 4% of your retirement portfolio in year one, then adjust for inflation annually, and your money will last at least 30 years with high probability. On a $1 million 401(k) balance, this equals $40,000/year or $3,333/month in sustainable income.
This calculator uses the 4% rule to show your estimated monthly retirement income. Add your expected Social Security benefit (average $1,907/month in 2026) for a more complete picture of retirement income.
401(k) Early Withdrawal Penalty
Withdrawing from your 401(k) before age 59½ results in a 10% penalty plus ordinary income tax on the full amount. On a $50,000 early withdrawal in the 22% tax bracket, you'd pay $11,000 in tax + $5,000 penalty = you keep only $34,000. Early withdrawal is almost never the right financial decision.
Frequently Asked Questions
How much should I contribute to my 401(k)?+
At minimum, contribute enough to get the full employer match — this is a 50–100% instant return. Beyond that, aim for 15% of gross income including employer match. If you cannot reach 15% immediately, increase by 1% each year when you get a raise. The best time to start maximizing contributions is always now.
What happens to my 401(k) if I leave my job?+
You have four options: leave it with your former employer (if allowed), roll it into your new employer's 401(k), roll it into an IRA (most flexible option), or cash it out (not recommended — triggers taxes and 10% penalty). Rolling to an IRA gives you the most investment choices and often lower fees.
What is the 2026 401(k) contribution limit?+
In 2026, the employee contribution limit is $23,500 per year. Workers aged 50 or older can make an additional catch-up contribution of $7,500, bringing their total to $31,000. These limits do not include employer contributions. The combined limit (employee + employer) is $70,000 in 2026.
When can I withdraw from my 401(k) penalty-free?+
Penalty-free withdrawals begin at age 59½. Required Minimum Distributions (RMDs) must begin at age 73 for Traditional 401(k) accounts. Roth 401(k) accounts are not subject to RMDs starting in 2024. Some exceptions to the 10% early withdrawal penalty apply — including first-home purchase, disability, and certain medical expenses.