What Is a 401(k)?

Updated on Wednesday, December 9, 2020

A 401(k) is a tax-advantaged savings and investing plan offered by many employers, allowing employees to contribute a portion of their wages to individual accounts intended to be used during their retirement years. However, 401(k) plans are not one size fits all, as they typically come in two types: a traditional 401(k) and a Roth 401(k). Both are effective ways to save for retirement, but diverge in important details, including how they are taxed.

• What is a traditional 401(k) and a Roth 401(k)?
• How does a 401(k) plan work?
• Why are 401(k) plans a good option for retirement savings?

What is a traditional 401(k) and a Roth 401(k)?

The two main types of 401(k) plans are traditional 401(k) plans and Roth 401(k) plans. While the retirement plans share core similarities, their differences diverge in the details.

Traditional 401(k) and Roth 401(k) plans are similar in the following ways:

• Both are employee-sponsored plans: To participate in either a traditional 401(k) or Roth 401(k), your employer must offer it as an option — you cannot simply shop around and sign up for one on your own. That’s because these are employer-sponsored plans, meaning your employer acts as the plan’s sponsor, and contributions come directly from your paycheck, before you even see the funds.
• Both allow for employer contributions: One of the biggest benefits of 401(k) plans is that they allow your employer to make contributions to your retirement fund on your behalf, which can ramp up your retirement savings significantly. Your employer may choose to match your contributions either dollar-for-dollar up to a certain amount — such as 5% of your annual salary — or make a partial match up to a certain amount. One concept to be aware of with employer matching contributions is vesting. Employers may require their employees to work at the company for a certain length of time before they actually own some or all of the matching contributions. Any amount you contribute from your own paycheck is yours from the moment it’s withheld.
• Both have the same contribution limits: Unlike a regular savings account or a taxable brokerage account, you cannot pile as much money as you want into your 401(k) plan. The IRS sets annual limits, and those caps are the same for both traditional 401(k) and Roth 401(k) plans. We hash out the contribution limits for 2021 later in this article.

The biggest difference between traditional 401(k) plans and Roth 401(k) plans is how they are taxed. Here’s how the two plans vary:

• How contributions are taxed: With traditional 401(k) plans, your contributions are made with pretax dollars deducted directly from your paycheck before any of your payroll taxes take effect. Meanwhile, Roth 401(k) contributions are made with after-tax dollars, meaning taxes are already withheld.
• How distributions are taxed: With traditional 401(k) plans, withdrawals are taxed as ordinary income. Meanwhile, Roth 401(k) withdrawals are not taxed, so long as they are a qualified distribution, which we flesh out later in this article.
• How early withdrawals are taxed: One of the defining characteristics of 401(k) plans is that they are designed to be nest eggs for your retirement years — and you generally cannot dip into them any time you want without facing a stiff penalty. Although there are exceptions, if you withdraw funds from a traditional 401(k) before you are 59 ½ years old, you will face a 10% tax penalty on the entire balance withdrawn. With a Roth 401(k), the tax penalty on early withdrawals (those made before the age of 59 ½ or if your account has been open for less than five years) is prorated between your non-taxable contributions and earnings. So, if your Roth 401(k) balance consists of $60,000, with $50,000 from contributions and $10,000 from gains made on those contributions, you will be taxed on only the percentage of your balance that represents your gains — plus a tacked-on 10% early withdrawal penalty, barring a few exceptions.

This chart quickly sums up the tax treatment of traditional 401(k) plans and Roth 401(k) plans:

How does a 401(k) plan work?

If your employer offers a 401(k) plan, make sure you put your contributions to work. Here’s how:

1. Make elective deferrals

With 401(k) plans, you will have to select how much you want to contribute per paycheck — these are called elective deferrals. You select the percentage of income you’d like withheld, and then that amount is deducted from each paycheck and deposited into your 401(k). As explained above, how those contributions are taxed will depend on whether you opt for a traditional 401(k) or a Roth 401(k). While many plans will auto-enroll you at a set contribution percentage, you should review how much you can afford to contribute to maximize any employer match and adjust accordingly.

Even the most ambitious savers are capped at how much they can contribute per year though. For both traditional 401(k) and Roth 401(k) plans, the contribution limits for 2021 are as follows:

2. Invest your contributions

Once your contributions are deposited into your 401(k) account, you have to decide where to invest those contributions. This is a common mistake that many savers make — simply signing up for and contributing to your 401(k) plan is not enough. If you don’t intervene, your plan might automatically keep much of your contributions in cash, where it will sit idly, as opposed to investing it in the market, where it has the potential to grow.

Many 401(k) plans offer a curated selection of mutual funds, ranging from conservative to aggressive, that you must choose from, which are managed and offered by a financial firm. After signing up for your 401(k) and selecting and making your elective deferrals, you have to choose which funds you want your contributions invested in. You can usually make these changes online after signing into your 401(k) account.

Factors to take into consideration when deciding how you to invest your contributions should include:

• Your risk tolerance
• Your time horizon
• Fees associated with the fund

In many cases, you might choose from a number of prebuilt, target date portfolios. These portfolios are typically made up of diversified investments with a certain target date in mind of when you want to retire. Your portfolio is then managed to be either more aggressive or more conservative based on how far away you are from that target date.

3. Don’t make withdrawals until you’re required to

Over time, you might change the rate of your contributions or your investment mix, but for the most part, you should sit back, relax and let your money grow untouched. In fact, even if you wanted to dip into your retirement account before your golden years, you will face heavy penalties if you do.

Typically, you cannot start making withdrawals from your 401(k) until the age of 59 ½. Withdrawals from your 401(k) made before this age are slapped with a tax penalty (the specifics of how those early withdrawals are taxed for both traditional and Roth 401(k) are noted above). There are certain exceptions to this rule, such as for cases of medical or financial hardship.

In addition, you can’t just let your contributions sit there and grow forever. In most cases, you must start taking required minimum distributions (RMDs) from your 401(k) once you turn 72 years old.

Why are 401(k) plans a good option for retirement savings?

While you can open a number of saving and investment vehicles to grow the funds pocketed away for your golden years, 401(k) plans offer an array of special advantages:

• They make it easy to save: By making your contributions before receiving your paycheck, you’re eliminating any temptation to spend those funds instead of saving them. Additionally, many plans will automatically increase the rate of your contributions annually, resulting in a stealthy way to save more. That consistency — coupled with a potential employer match — can result in significant savings over time.
• They offer tax benefits: Whether you opt for a traditional 401(k) or a Roth 401(k), you’ll enjoy some sort of tax benefit. By contributing to a traditional 401(k) with pretax dollars, you’ll reduce your taxable income for that year. Meanwhile, Roth 401(k) plans give you a tax break in the future, when you might be making more income and find yourself in a higher tax bracket.
• They can come with you when you change jobs: If you’re leaving your job and the 401(k) plan that comes with it, you don’t have to leave your funds behind. Take your retirement savings with you as a 401(k) rollover, which entails moving your 401(k) funds from your old job’s 401(k) plan over into a new 401(k) plan at your new job. This way your funds aren’t left behind, yet you don’t have to cash out and get hit with a big tax bill.