What is a 401(k) and Are You Actually Using Yours Right?

If you work for a company with more than a handful of employees, there's a good chance you have access to a 401(k). And if you're like most American workers, you enrolled during your first week of work, picked something in the middle of the investment list, and haven't thought about it since.

That's not uncommon — but it may be costing you significantly over time. Understanding how a 401(k) actually works puts you in a position to make it work for you, not just passively alongside you.

What is a 401(k)?

A 401(k) is an employer-sponsored retirement savings account that allows you to set aside a portion of your paycheck before taxes are applied. The name comes from Section 401(k) of the Internal Revenue Code. The core benefit is tax-advantaged growth — your money compounds over time without being taxed year over year, making a significant difference over decades.

Traditional 401(k) vs. Roth 401(k)

• Traditional 401(k): Contributions are pre-tax, reducing your taxable income today. You pay income taxes when you withdraw in retirement.
• Roth 401(k): Contributions are after-tax — no immediate break — but qualified withdrawals in retirement are completely tax-free, including all growth.

2025 Contribution Limits

The Employer Match: Free Money You Shouldn't Leave Behind

Many employers match a portion of your contributions — typically 50%–100% up to a percentage of your salary. If you're not contributing enough to capture the full match, you're leaving compensation on the table. This is widely considered the most important first step in retirement planning.

Vesting: When Is the Employer Match Actually Yours?

Employer contributions often come with a vesting schedule. Common structures include immediate vesting, cliff vesting (100% after a set period), and graded vesting (incrementally over time). If you're considering changing jobs, knowing your vesting status matters — leaving before full vesting means forfeiting unvested funds.

Investment Options Inside Your 401(k)

Your 401(k) is a container, not an investment itself. You choose from a menu your employer provides:

• Target-date funds: Automatically adjust allocation as you approach retirement. A reasonable default for most workers.
• Index funds: Track a market index like the S&P 500. Generally preferred for low expense ratios and broad market exposure.
• Actively managed funds: Higher fees; research consistently shows they underperform index funds over the long term.

Pay Attention to Expense Ratios

Every fund charges an annual percentage fee. High fees compound into meaningful drag over decades. Target expense ratios below 0.20% — many index funds charge 0.03%–0.10%.

Are You Actually Using Yours Right?

• ✓ Contributing at least enough to capture the full employer match?
• ✓ Do you know whether you have a traditional, Roth, or both?
• ✓ Have you reviewed your investment allocation in the past year?
• ✓ Do you know your expense ratios?
• ✓ Do you know your vesting schedule?
• ✓ Are you increasing your contribution as your income grows?

What to Do If You've Changed Jobs

When you leave an employer your options are: leave the balance in the former plan, roll it into your new employer's plan, roll it into an IRA, or cash it out. Cashing out is generally the worst option — you'll owe income taxes plus a 10% early withdrawal penalty if you're under 59½. Most financial professionals recommend rolling old balances into an IRA or current employer plan to keep savings consolidated and growing.