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You know that 401(k) plans let you save relatively large amounts of money for retirement every year, but one of the biggest hassles with them is that they're tied to your particular employer. Once you leave your old job, you can't make further contributions. As a result, most people roll over their old 401(k) accounts when they switch jobs, either moving the money into an IRA or transferring it to the 401(k) plan at their new employer. Often, that's a smart move, but there are a few cases where you're better off leaving your old 401(k) alone.

1. When your old 401(k) has superior investment features.
All too often, 401(k) participants can't wait to get out of their old employer's plans. With limited investment options, often-costly mutual fund choices, and a host of other fees that can be difficult to learn about, the typical employer's 401(k) plan leaves a lot to be desired.

Sometimes, though, you'll run into an employer that has a great 401(k) plan. Large employers often have access to institutional classes of mutual funds, with expenses that are far lower than you'll be able to get on your own working through a broker or other investment professional. Moreover, high-quality 401(k) plans have investment menus that include desirable fund choices that you'd have trouble improving on outside the plan anyway. If your old employer's plan has these desirable features and also doesn't charge administrative fees or other costs, then leaving your money there can be the best way to implement part of your retirement saving strategy.

2. When you expect to withdraw money in your mid- to late-50s.
IRAs and 401(k) plan accounts have a lot in common. But there are a few key differences, and one of the most important affects those who choose to take early distributions, such as early retirees.

If you have a traditional IRA and want to start taking withdrawals, you have to be at least age 59 1/2 in order to avoid early withdrawal penalties. Sometimes, you can get out of those penalties if you make withdrawals for certain purposes, such as a home purchase or educational expenses. If an exception doesn't apply, though, then you'll pay 10% extra for access to your money, on top of the withdrawal being included in your taxable income.

However, 401(k) plans have a different early withdrawal penalty standard. With a 401(k), you can start making withdrawals as early as age 55, as long as you no longer work for that company. That rule covers you whether you've retired early or you've simply switched to a different employer.

However, if you roll over that 401(k) into an IRA, you lose the benefit of the age 55 rule. Therefore, if you anticipate needing access to your retirement savings between age 55 and 59 1/2 -- whether it's for early retirement or for other purposes -- then leaving your old 401(k) in place can make it far easier to get at that money without paying a penalty.

3. When you have highly appreciated company stock in your old 401(k).
Many workers invest their 401(k) assets in company stock, and in some cases, their stock has climbed in value substantially over the course of your career. Although you can roll over your 401(k) to an IRA tax-free, you'll eventually have to pay taxes when you withdraw your retirement assets at full ordinary-income rates.

A special rule offers better tax treatment for company stock. Instead of rolling it over, you can arrange to have company stock distributed directly to a taxable account. You'll pay ordinary income taxes on the initial value of the stock when you bought it in your 401(k), but you'll be able to defer any gains since then. Moreover, when you do sell your stock, you can qualify for long-term capital gains treatment and pay less in taxes overall.

Most of the time, it makes sense to roll over your old employer 401(k) when you leave a job. In these cases, though, you should think twice before making a switch. You might end up better off sticking with what you have.

Dan Caplinger has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.