You've left your job. What should you do with the 401(k) plan you've faithfully contributed to for years? Conventional wisdom says roll it over into an Individual Retirement Account (IRA), and in many cases, that is the best course of action (see 8 Reasons to Roll Over Your 401(k) to an IRA). But there are times when a rollover is not your best option. We take a look at five of those situations, and the rationale for keeping your 401(k) – or, if you're a public or nonprofit employee, your 403(b) or 457 plan – in place.

1. Greater Buying Power

Company 401(k)s can purchase funds at institutional pricing rates, which is not usually true for IRAs. Think of it as a kind of corporate discount: Because they're investing for hundreds of thousands, “most 401(k), 403 (b) and 457 plans have significant buying power – much more than the individual [retirement account],” says Wayne Bogosian, president of the PFE Group and co-author of “The Complete Idiot’s Guide to 401(k) Plans.” That can save you significant money on fees, leaving more to appreciate in your own account.

2. Tax Savings

If your 401(k) plan includes company stock that's greatly appreciated, you could save a lot on taxes if you transfer that stock to a regular brokerage account. You will have to pay taxes on the shares taken out of your 401(k), at your current bracket's rate, but the tax is based on your original purchase price – you won’t pay for any gain on that stock until you actually sell it (and then you'll pay at the capital gains tax rate, which is lower than the income tax rate). This is known as Net Unrealized Appreciation.

"NUAs are a tremendous opportunity for individuals with appreciated company stock in their 401(k)," says investment advisor representative Jonathan Swanburg of Tri-Star Advisors in Houston, Texas.

For example, suppose the company stock was bought for $10,000 and is currently worth $50,000 on the market. Your tax bill for transferring the stock to the brokerage firm will be based on the $10,000 purchase price. You won’t be taxed on any of the gain until you sell it. In contrast, if you rolled over that stock into an IRA, it would eventually be taxed at your ordinary income tax rate (when you have to sell the stock to start taking your mandatory IRA distributions).

Two cautions:

  • Make sure the holdings in your 401(k) are actual stock shares; some 401(k)s set up a fund that mimics the corporate stock's performance.
  • Make sure the transfer of these holdings doesn't put such a sizeable bump in your income that you get pushed into a higher tax bracket – and end up owing the Internal Revenue Service much more than otherwise come next April.

"If, on the other hand, a plan participant holds depreciated company stock that she plans to hold until the price goes higher, she should consider selling her shares and repurchasing them shortly thereafter," Swanburg adds. "Inside a 401(k), the wash-sale rule doesn’t apply and this resets the cost basis, increasing the potential for taking advantage of the NUA down the road."

3. Legal Protection

Money held in a 401(k) is protected by federal law from pretty much all types of creditor judgments (other than IRS tax liens and possibly, spousal or child support orders), including bankruptcy. IRAs are only protected by state law, whose shielding power varies. The Bankruptcy Abuse Prevention and Consumer Protection Act of 2005, does protect up to $1 million (inflation-adjusted to $1.2 million as of 2014) in traditional or Roth IRA assets against bankruptcy. But protection against other types of judgments varies by state and may even be different depending on whether your IRA is a Roth or the traditional form.

If you are concerned about potential judgments, creditors or collections, keeping your 401(k) funds in place might afford the most safety.

4. Early Retirement Benefits

“One of the most important reasons not to roll over your 401(k) to an IRA is to have access to your funds before age 59½," says Marguerita Cheng, CFP®, chief executive officer of Blue Ocean Global Wealth in Rockville, Md. "They can be accessed as early as age 55 versus having to pay a 10% early withdrawal penalty in an IRA.”

In fact, you may be able to do withdraw money from your 401(k) after you leave multiple times each year (the employer sets the rules about how many times people in this age group can withdraw funds). Once you roll the 401(k) into an IRA you lose this privilege, and you'll have to wait until age 59½ to access your money without penalty.

5. Stable Value Funds

Company 401(k) plans have access to a special type of fund called a stable value fund. Not available in the individual market, these funds are similar to money market funds, but they offer better interest rates – an average of 2.73% at this writing. If you'd like to take advantage of these risk-averse vehicles, and your 401(k) offers them as an option, definitely stick to your current plan.

The Bottom Line

When you and your job part ways, the decision about what to do with your retirement savings is a big one. Rolling over a 401(k) may be the best option for you in most cases, but there are reasons that leaving the money in the company fund could work better. Do check your company's rules, though: Most employers require your 401(k) to maintain a certain minimum sum if you want to leave the account in place after your employment ends, and there may be differences in your access, fund-allocation privileges and fees, too.

One other option to investigate if you want to keep your money in a 401(k) and you're leaving your old job for a new one: rolling over the money in your previous job's plan into the one at your new company.

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