If you work for a company that offers a 401k and you’re not using it – or you’re using it but not entirely sure what it is – this is for you.
A 401k is a retirement savings account tied to your employer. You put money in from your paycheck before taxes hit it, it grows tax-deferred, and you pay taxes when you take the money out in retirement. That’s the core of it. Everything else is just details.
The name comes from the section of the IRS tax code that created it – Section 401(k). Not a particularly inspiring name, but the account itself is one of the most powerful financial tools available to working Americans.
How Contributions Work
When you enroll in your employer’s 401k plan, you choose what percentage of each paycheck goes in. That money is deducted before federal income taxes are calculated, which means you’re reducing your taxable income today while building savings for later.
If you earn $60,000 a year and contribute 10%, you’re putting $6,000 into your 401k. But your taxable income for the year drops to $54,000. Depending on your tax bracket, that saves you real money now while your investments grow.
The 2026 contribution limit for a 401k is $23,500. If you’re 50 or older, you can contribute an additional $7,500 in catch-up contributions, bringing your total to $31,000. These limits are set by the IRS and typically increase slightly each year with inflation.
Most people don’t max out their 401k – and that’s fine. The goal isn’t perfection, it’s consistent progress. Contributing even 6-10% of your income from early in your career produces results that are hard to replicate by starting later with more money.
The Employer Match – Free Money You Should Never Leave Behind
Many employers match a portion of what you contribute. A common structure is something like “we match 50% of your contributions up to 6% of your salary.” In plain terms: if you earn $60,000 and contribute 6% ($3,600), your employer adds another $1,800.
That’s an immediate 50% return on those dollars before the market does anything. There is no investment on earth that guarantees a 50% return. Not taking the full employer match is, without exaggeration, turning down part of your compensation.
Before you do anything else with your retirement savings, contribute at least enough to get the full employer match. Everything beyond that is a separate conversation.
One catch – employer contributions often come with a vesting schedule. This means the employer match isn’t fully yours until you’ve worked there for a certain number of years. A typical vesting schedule might be 25% per year over four years, meaning if you leave after two years you only keep half the employer contributions. Check your plan documents to understand your vesting schedule before making job decisions.
Traditional 401k vs Roth 401k
Many employers now offer both a traditional 401k and a Roth 401k option. The difference comes down to when you pay taxes.
With a traditional 401k, contributions come out of your paycheck before taxes. You get the tax break now. You pay taxes when you withdraw in retirement.
With a Roth 401k, contributions come out after taxes. No tax break now. But qualified withdrawals in retirement are completely tax-free – including all the growth.
Which is better depends on where you think tax rates are headed and what tax bracket you expect to be in during retirement. If you’re early in your career and in a lower tax bracket now than you expect to be later, the Roth option often makes more sense. If you’re in your peak earning years and a high tax bracket, the traditional option and its immediate tax deduction may be more valuable.
A lot of people split the difference and contribute to both. That’s a reasonable hedge if your plan allows it.
What Happens to Your 401k When You Leave a Job
This is where a lot of people make expensive mistakes.
When you leave an employer, you have a few options for your 401k balance. You can leave it in the old employer’s plan if they allow it, roll it over into your new employer’s plan, roll it into an IRA, or cash it out.
Do not cash it out. If you withdraw the money before age 59½, you’ll owe income taxes on the full amount plus a 10% early withdrawal penalty. On a $30,000 balance in the 25% tax bracket, that’s $10,500 gone immediately. People do this constantly, usually because they need the money or don’t know what else to do, and it’s one of the most damaging things you can do to your long-term retirement savings.
Rolling your balance into an IRA or your new employer’s 401k costs nothing, keeps the money growing tax-deferred, and gives you full control. It’s almost always the right move.
What Your Money Is Actually Invested In
Your 401k contributions don’t just sit in a savings account. They’re invested in funds – typically mutual funds or index funds – that your employer has selected for the plan.
Most 401k plans offer a menu of options ranging from conservative bond funds to aggressive stock funds, with target-date funds somewhere in the middle. A target-date fund is designed to automatically shift toward more conservative investments as you approach retirement. If your plan offers a target-date fund close to your expected retirement year, it’s a reasonable default for people who don’t want to actively manage their allocations.
The most important thing is that your money is actually invested, not sitting in a money market or default cash option. Some plans default new enrollees to cash or stable value funds, which means your contributions are growing at almost nothing while you think you’re investing. Log into your plan and verify where your money is going.
Early Withdrawal and Loans
Life happens, and sometimes people consider tapping their 401k early. The rules are strict for good reason.
Withdrawals before age 59½ trigger income taxes plus that 10% penalty in most cases. There are hardship withdrawal provisions for things like medical expenses or preventing foreclosure, but these vary by plan and still typically trigger taxes.
Many plans also allow 401k loans – borrowing from your own balance and repaying yourself with interest. This sounds attractive but has real risks. If you leave your job while carrying a loan balance, the outstanding amount is typically due within 60-90 days or it’s treated as a withdrawal and taxed accordingly. In a job loss or career change, that’s exactly when you can least afford a surprise tax bill.
Treat your 401k as untouchable until retirement. That’s what it’s for.
Required Minimum Distributions
Once you reach age 73, the IRS requires you to start withdrawing a minimum amount from your traditional 401k each year, whether you need the money or not. These are called Required Minimum Distributions (RMDs). The amount is based on your account balance and life expectancy tables published by the IRS.
If you’re still working at 73 and contributing to your current employer’s 401k, you may be able to delay RMDs from that specific account. But old 401k balances and traditional IRAs are subject to RMDs regardless.
Roth 401k accounts inherited the same RMD rules as traditional 401ks, but if you roll a Roth 401k into a Roth IRA, the Roth IRA has no RMD requirements during your lifetime. This is one reason some people do that rollover.
The Bottom Line
A 401k is straightforward once you understand the basics. Money goes in before taxes, grows tax-deferred, and comes out taxed in retirement. Your employer may add free money through a match. The contribution limit in 2026 is $23,500, or $31,000 if you’re 50 or older.
The biggest mistakes people make are not contributing enough to capture the full employer match, cashing out when they change jobs, and not knowing what their money is actually invested in.
If you’re not enrolled in your employer’s 401k and one is available to you, that’s the single most important financial step you can take today. Get the full details on contribution rules and limits directly from the IRS at irs.gov/retirement-plans/401k-plans.