Your First 401(k): What to Actually Do With It

Starting a new job usually comes with a stack of paperwork, and somewhere in that stack is a decision about your 401(k). Most people either skip it entirely or pick something at random because nobody explained what any of it means.

That's a costly thing to get wrong — or to skip. So here's the plain-English version: what a 401(k) actually is, the one number that matters most, and the handful of decisions you need to make.

What a 401(k) actually is

A 401(k) is a retirement account that your employer offers. You contribute money straight from your paycheck — before you ever see it — and that money gets invested so it grows over the decades until you retire.

The big appeal is the tax advantage. With a traditional 401(k), the money goes in before taxes, which lowers your taxable income today. You pay taxes later, when you withdraw it in retirement. (There's also a Roth 401(k) option at many employers, where you pay taxes now and withdraw tax-free later — similar to a Roth IRA.)

The one number that matters most: the employer match

If you remember nothing else from this article, remember this: many employers will match a portion of what you contribute, and that match is free money.

A common match looks like this: "We'll match 100% of your contributions up to 4% of your salary." That means if you earn $50,000 and contribute 4% ($2,000), your employer drops in another $2,000. You just doubled your money instantly, before it's even invested.

Skipping the match is so costly that it's worth contributing enough to capture it even while you're paying down debt or building your emergency fund. A guaranteed 100% return beats almost any interest rate you're fighting.

How much can you put in?

For 2026, the IRS lets you contribute up to $24,500 of your own money to a 401(k). If you're 50 or older, you can add an extra $8,000 in catch-up contributions. Those are ceilings, not targets — most people starting out contribute far less, and that's completely fine.

A reasonable progression for most people:

1. Start by contributing enough to get the full employer match (often 3–6%)
2. As your income grows, work toward contributing 10–15% of your salary total
3. If you ever max it out, congratulations — you're in great shape

The step everyone forgets: actually investing the money

Here's a mistake that's more common than you'd think. People set up their 401(k), money starts coming out of their paycheck, and they assume it's being invested. But in many plans, contributions sit in a default holding account until you choose investments.

When you set up your 401(k), you'll be asked to choose funds. For most people, the best choice is one of these two:

• A target-date fund. These are named for the year you plan to retire — like "Target Retirement 2060." You pick the one closest to your retirement year, and the fund automatically handles everything: a mix of stocks and bonds that gradually gets more conservative as you age. It's the genuine set-it-and-forget-it option.
• A low-cost index fund. If your plan offers an S&P 500 or total market index fund with low fees, that's a solid choice too.

Avoid funds with high expense ratios (anything over about 0.5% per year) if you have cheaper options. Over decades, high fees quietly eat a large chunk of your returns.

What "vesting" means (and why it matters if you might leave)

Your own contributions are always 100% yours. But the employer match sometimes comes with a vesting schedule — meaning you have to stay at the company for a certain period before that matched money is fully yours to keep.

A typical schedule might vest 25% per year over four years. If you leave after two years, you'd keep your own contributions plus 50% of the match. It's worth knowing your plan's vesting schedule, especially if you're thinking about changing jobs.

What happens to your 401(k) when you leave a job?

You have a few options, and you don't lose the money. You can leave it in the old employer's plan, roll it over into your new employer's 401(k), or roll it into an IRA. Rolling it into an IRA often gives you more investment choices and lower fees. What you generally want to avoid is cashing it out — you'll owe taxes plus a 10% penalty if you're under 59½, and you'll lose decades of potential growth.

401(k) vs. Roth IRA: which comes first?

If you have access to both and can't max out both, a common order of operations is:

1. Contribute to your 401(k) up to the full employer match (free money first)
2. Then put additional retirement savings into a Roth IRA (more investment flexibility, tax-free withdrawals)
3. If you still have money to invest after maxing the Roth IRA, go back and contribute more to the 401(k)

This order captures the free match first, then takes advantage of the Roth's flexibility, then uses the 401(k)'s high contribution ceiling for anything beyond that.