When you change jobs, or stop working, you have to decide what to do with the money in your 401(k). You have a number of choices and the one that makes the most money will be different depending on your circumstances.

It probably doesn't make sense to take a lump-sum payout. Unless you're at least 59½ (or meet some other very specific exceptions), you're going to pay a 10% penalty for an early withdrawal. (See What Is the penalty for taking money out of my 401(k) before I'm 59 years old?) Even if you are past that age, you will likely trigger a pretty hefty tax bill. Instead, you're probably looking to roll over the account to something else – but where should it go?

If you own company stock as part of your 401(k), you need to know about net unrealized appreciation, or NUA. NUA allows you to roll your company stock into a regular brokerage account and pay long-term capital gains on your earnings instead of ordinary income tax on them.

Kevin Clark, of Quintessential Retirement Services, says, Using NUA, one would have to take their employer stock as shares – [they] cannot be liquidated and sent – and set up in a brokerage account outside of the 401(k). The participant would then be taxed on the cost basis – not the account value – at a long-term capital gain rate, not the ordinary income tax rate used for 401(k)s or IRAs. The current long-term capital gains rate (see What You Need To Know About Capital Gains And Taxes) is maxed out at 20% versus 39.6%, plus all of the Medicare and additional taxes if one's income is over $250,000.

You can't do that with the entire account, but using NUA will probably let you pay considerably less on the gains earned from your company stock.

For more information, see Rolling Over Company Stock: A Decision To Think Twice About.

Tips:

• Figure out how much of your 401(k) balance is company stock.
• Ask a financial advisor about NUA and whether it applies to you.

Not all employers will allow you to do this but if your new company does, take a good look at the investment options available in its 401(k). If there are better options than where your money is now – and, equally important, if the new company's fees are lower – this may be a good idea if you don't want to manage the funds yourself or and don't have a financial advisor.

To find out if this is an option, read the documents that come with your new 401(k), ask your HR department or call the investment firm handling the account.

Tips:

• Ask your new employer if you have the option to roll your old 401(k) into its plan.
• Evaluate whether the investment options in your new employer's plan are better or the same as what you had before. Only roll the account to your new employer if the investment options and fees are the same or better – or your old employer won't let you keep the funds in the old account.
• Figuring out the fee structure isn't always easy. Ask the broker to break down the fees for you.

This is always a popular choice. Rolling the money to an IRA gives you complete control over your money. Do you want to invest in individual stocks? You can. How about options or MLP​s? You can – to a degree. IRS rules prevent you from using your account as collateral so you can't sell short or have a margin account, but most everything else is allowed. Brokers vary in their rules so ask before you roll over.

Don't forget about NUA and if you're in the market to roll an account over, do a little shopping. Brokers are eager to get your business and may offer an incentive, often in the form of free cash, to get your business. Don't evaluate on freebies alone but if they're willing to give you free cash, that might count for something. For examples of what you might find, see Best 2015 IRA Promotions.

Tips:

• Ask a financial advisor about the benefits of rolling over to a Roth vs. a traditional IRA. There are many scenarios to consider with this.
• Don't forget about NUA if you're considering rolling a 401(k) that held company stock.
• Shop around. Look at transaction costs, find an advisor who offers freebies or incentives that come with rolling your account over to him or her (see Rolling Over a 401(k)? Consider the Fees).
• Ask your old 401(k) custodian to transfer the funds to your new broker. Do not take custody of the money yourself to avoid any potential tax difficulties.

Nobody said you have to roll over the account. Just because you left the job the 401(k) was tied to doesn't mean the money has to leave the brokerage firm that held it. In fact, the firm would probably be more than happy to keep managing your money.

Because 401(k)s come in many shapes and sizes, only a financial advisor can help you evaluate the decision. Especially if your account is large, don't make this decision without some help from an expert. For more information, see 5 Benefits of Rolling Over a 401(k) and Best Ways to Roll Over Your 401(k).