Understanding Your 401k

Understanding Your 401k

The 401(k) is the most widely available retirement savings account in America, and for most employed workers it is the foundation of long-term wealth building. Yet many people contribute to one for years without fully understanding how it works, what it costs, or how to use it effectively. This lesson changes that.

What a 401(k) Actually Is

A 401(k) is an employer-sponsored retirement savings plan that allows you to contribute a portion of your paycheck before taxes are taken out. That pre-tax contribution reduces your taxable income in the year you make it -- which means you pay less in income tax right now. The money then grows tax-deferred inside the account until you withdraw it in retirement, at which point it is taxed as ordinary income.

For nonprofit employers like hospitals, universities, and charities, the equivalent plan is called a 403(b). It functions identically to a 401(k) for most purposes.

The Contribution Limit

In 2024, you can contribute up to $23,000 of your own money to a 401(k). If you are age 50 or older, you can contribute an additional $7,500 as a catch-up contribution, for a total of $30,500. These limits apply to your contributions only -- employer matching contributions are on top of this amount.

The Employer Match: Free Money

Many employers match a percentage of employee contributions -- often 50% to 100% of contributions up to 3% to 6% of salary. This match is part of your total compensation, and failing to contribute enough to capture it in full is one of the most common and costly financial mistakes working adults make.

If your employer matches 50% of contributions up to 6% of your salary and you earn $70,000, contributing 6% ($4,200) earns you a $2,100 employer match -- a guaranteed 50% return before any investment growth. There is no investment that reliably competes with this.

Investment Options Inside a 401(k)

Unlike an IRA, a 401(k) limits your investment choices to the funds selected by your employer plan. Most plans offer a range of mutual funds and index funds. When choosing investments inside your 401(k), look for:

Low expense ratios. The expense ratio is the annual fee charged by the fund, expressed as a percentage of assets. A fund charging 0.05% costs you $5 per year on $10,000 invested. A fund charging 1.00% costs you $100 on the same amount. Over 30 years, this difference compounds into tens of thousands of dollars. Choose the lowest-cost options available.

Broad diversification. A total market index fund or an S&P 500 index fund provides instant exposure to hundreds or thousands of companies. Avoid concentrating your retirement savings in your employer stock or a single sector fund.

Target-date funds. Many plans offer target-date funds labeled by expected retirement year (such as a 2055 Fund). These automatically shift from aggressive to conservative as the target date approaches. They are a reasonable default choice for investors who prefer simplicity.

Early Withdrawal Penalties

Withdrawals from a 401(k) before age 59½ are generally subject to a 10% early withdrawal penalty on top of ordinary income taxes owed. This is why retirement accounts should be treated as long-term vehicles -- the early withdrawal penalty effectively makes them expensive sources of emergency cash. Build an emergency fund outside of retirement accounts before contributing beyond the employer match.

Key Takeaway

Contribute at least enough to capture the full employer match -- every dollar of match left on the table is a dollar of compensation forfeited. Choose low-cost index funds where available. Avoid early withdrawals. The 401(k) is the most powerful tax-advantaged tool available to most employees -- use it fully and use it well.