Seven 401(k) Mistakes That Could Tank Your Retirement

One of these 401(k) mistakes could cost you $300,000. Others could upend your retirement.

A retired couple look over retirement paperwork to check for 401(k) mistakes.
(Image credit: Getty Images)

When it comes to potential 401(k) mistakes, it pays to listen to the investing gurus. Warren Buffet once said, “Rule No. 1: Never lose money. Rule No. 2: Never forget rule No. 1.” Wise advice, especially when planning your retirement, where there may not be time for do-overs in your 401(k) plans. As most Americans can no longer rely on pensions for retirement, and as Social Security risks running out of money in the next decade, the humble 401(k) plan is the workhorse for most people's retirements.

Two new studies — from Vanguard and GoBankingRates — show how Americans mismanage their 401(k) accounts. One of these mistakes could cost you $300,000 over your working lifetime. We've unpacked these blunders and five others to help you safeguard your 401(k). Fortunately, it only takes a little planning to avoid the worst 401(k) mistakes.

401(k) mistakes that can cost you

Experts agree that a 401(k) is one of the best ways to save for retirement. With a 401(k), you get both tax advantages and employer matching (if available), which can add substantially to your contributions. Plus, if you automate your savings, your contribution limits can be significantly higher than with individual retirement plans.

Subscribe to Kiplinger’s Personal Finance

Be a smarter, better informed investor.

Save up to 74%
https://cdn.mos.cms.futurecdn.net/hwgJ7osrMtUWhk5koeVme7-200-80.png

Sign up for Kiplinger’s Free E-Newsletters

Profit and prosper with the best of expert advice on investing, taxes, retirement, personal finance and more - straight to your e-mail.

Profit and prosper with the best of expert advice - straight to your e-mail.

Sign up

An astonishing 33% of middle-class Americans are cashing in their retirement investments before they retire, which can leave them at risk of poverty as they age, according to recent data from the Transamerica Institute. The Lonely Office, a podcast about navigating the messy line between work and life, recently covered the pros and cons (mostly cons) of pulling from your 401(k) fund. Some people may not realize that when you withdraw money from your 401(k) before the age of 59 1⁄2, you are subject to a 10% early withdrawal penalty, in addition to any other income taxes you might owe.

After interviewing several people, the podcast drew two conclusions: taking money out of your 401(k) early and paying a penalty must mean you are either running out of money or you're unaware of the downsides.

Here are seven 401(k) mistakes to avoid as you plan for or enter retirement.

1. Switching jobs

A new Vanguard study showed that 55% of job switchers reduced their 401(k) nest egg by $300,000 over their working lives by failing to adjust their savings rate to higher salaries. Most employees (64%) experienced a 10% boost to their income when they switched jobs, but less than half did the smart thing: increasing or, at least, maintaining their savings rate from their prior job. Most people effectively decreased their savings rate in their new job.

The study also revealed that the outcome was far worse when an employer offered voluntary enrollment in a 401(k) plan versus an automatic enrollment. All the same, even those who were automatically enrolled in a plan had losses, too. That's because 60% of enrollees stuck to the default savings rate, often only a 3% rate.

It's easy to forget to increase your 401(k) contributions in line with your income. However, the result is that as you become accustomed to a higher salary, you underfund the same standard of living in your retirement.

2. Forgotten 401(k)s

401(k) accounts don’t automatically transfer when employees change jobs. That may be one reason why, in May 2023, there were 29 million forgotten 410(k) accounts, accounting for over $1.6 trillion in lost money floating around, according to data from Capitalize. Forgetting a 401(k), especially if you change jobs often, can mean landing a job and starting a 410(k), then moving on to another company and forgetting to transition the 410(k) or roll it over.

3. Not knowing your 401(k) investments

It’s not uncommon for employees, especially if automatically enrolled, to overlook how their funds are invested. That's a mistake, as you need to adjust your risk level as you age, from more growth in your early years to more stable, fixed-income investments as you age. Many people use target date funds in their 401(k)s to meet this need, automatically adjusting their risk level as they age.

Another downside of ignoring your 401(k) holdings is failing to get a handle on what fees you may be paying. High fees leave less in your account to compound over time. At the very least, you should review your 401(k) plan's annual fee disclosure statement. Better yet, take the time to log into your account periodically to check your fees and investments. If you feel the fees stated are high, consider investing only enough in your 401(k) to qualify for your employer match and save the rest in an IRA instead, which also offers tax advantages.

4. Not taking advantage of employer match

Many employers offer employee matching, which means any contributions you make to your 401(k) are matched by your employer, usually up to a set percentage of your salary. If you don’t contribute enough to qualify for employer matching, you are essentially leaving money on the table.

5. Not being vested

If your employer offers 401(k) matching, you can’t keep that money until you're fully vested. Be sure you understand your employer's vesting rules, which may allow you to keep the matched portion of your 401(k) after a set number of years or may be incrementally phased in. Though you keep your own 401(k) contributions if you leave your job before the vesting period ends, you lose the matched portion.

6. Taking an early withdrawal 

Cashing out your 401(k), taking a 401(k) loan, or hardship withdrawal are some of the worst mistakes you can make if you're counting on the money from your 401(k) when you retire. Understandably, if you’re in a tight spot and need money to pay for basic necessities, raiding your 401(k) may not be an option you can walk away from.

However, cashing out your 401(k) before age 59½ means that money will likely be subject to a 10% penalty on top of any income tax you owe. And although many plans allow for loans or hardship withdrawals, these withdrawals usually incur fees. Cashing out retirement money early is clearly a major negative and contributes to why many people have so little saved for retirement.

7. Not rolling over an old 401(k) 

You can typically opt to leave your 401(k) where it is (with your old employer), roll it into an IRA, or move it into your new employer’s 401(k) plan. Sometimes, parking your money indefinitely in an old employer's plan is the wrong move.

If your account has under $7,000 invested under a previous employer's plan, they may decide to distribute the amount to you or roll it into an IRA under the "forced plan distribution" rule. Not only is this a bureaucratic headache, you will have to pay taxes on any distributions.

If your 401(k) balance is between $1,000 and $7,000, your former employer may be able to help you roll the funds into your new employer's 401(k) plan.

Finally, if you change jobs often, you may mistakenly leave 401(k) plans floating around that can be easy to forget or lose track of.

Just as the Vanguard study showed 55% of job switchers reduced their 401(k) nest egg by, on average, $300,000 when they switched jobs, not rolling over an old 401(k) when you move to another company might be an expensive mistake.

On the other hand, there are some advantages to keeping a 401(k) in your former employer's plan. First, if the plan has superior investments or lower fees than your new employer's plan, you might want to keep your old plan as-is. Second, if you plan to retire early, you might want to take advantage of the "rule of 55." This IRS rule allows individuals who leave their job during or after the year they turn 55 to withdraw funds from their 401(k) without the 10% early withdrawal penalty. By rolling over an old 401(k) into an IRA, you lose the ability to take advantage of the rule of 55.

Reasons why people withdraw from their 401(k) early

A study by GoBankingRates, “5 Reasons the Middle Class Is Withdrawing From Their Retirement Accounts Early," cites several reasons why people extract money from their 401(k) before retirement.

  • Financial emergencies. Major car or home repairs, family emergencies, and other unexpected costs can add up quickly. Before you turn to your 401(k) savings, read Kiplinger's advice on preparing for a financial emergency.
  • Paying down debt or for everyday expenses. You might tap into your 401(k) early because of a job loss or the inability to find a new job, credit card and/or student loan debt. Instead of tapping your 401(k), check out our solutions for paying off credit card debt.
  • Paying for unexpected medical bills. The report from Transamerica reveals that 20% of those who dip into their retirement accounts say medical bills are the main reason.

Bottom line

Many experts advise replacing 80% of pre-retirement income for a comfortable lifestyle post-retirement. Although that may sound like a lot or be impossible for some people, according to Northwestern Mutual’s 2024 Planning & Progress Study, most retirees surveyed believe they will need $1.46 million in the bank to retire comfortably. That’s a 15% increase over last year — far outpacing the 3% to 5% inflation rate — and is up 53% from 2020.

That’s also a sharp contrast to the average amount that most adults have saved for retirement — a meager $88,400 compared to $89,300 in 2023. Given that 11,000 Americans will turn 65 every day through 2027, only half of Boomers and Gen Xers believe they’ll be financially ready for retirement when the time comes. Avoiding these seven 401(k) mistakes now that could imperil your retirement later on can save you many sleepless nights. That much you owe to yourself.

Related Content

Kathryn Pomroy
Contributor

For the past 18+ years, Kathryn has highlighted the humanity in personal finance by shaping stories that identify the opportunities and obstacles in managing a person's finances. All the same, she’ll jump on other equally important topics if needed. Kathryn graduated with a degree in Journalism and lives in Duluth, Minnesota. She joined Kiplinger in 2023 as a contributor.