Retiring soon? Take these steps to ease post-career anxiety

Once retirement begins, you're left to handle the often challenging transition from receiving a regular paycheck to creating your own income stream from retirement assets. It means a shift in mind-set—switching from putting money into retirement accounts to withdrawing money from them.

Whether you have two retirement savings accounts or five, you'll want to take certain steps to streamline your inflows, outflows and financial accounts so that you can spend more of your time enjoying retirement rather than managing it.

1. Estimate your total expenses. The first thing you'll need to do is total up your anticipated annual expenses so that you know how much income you'll need to cover them. A good rule of thumb is to save at least eight times your preretirement salary to increase the chances that you won't outlive your savings.

Ideally, you want to start saving in your 20s because the earlier you start saving, the more time your money has to grow. However, if you're in your 30s, 40s or even 50s and you haven't started saving, you're not alone.

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About one-third of the people in the U.S. have nothing saved for retirement, according to a Bankrate.com survey. In fact, 33 percent of them are ages 30 to 49, and 26 percent are 50 to 64. The most important thing to remember is that no matter how old you are, it's never too late, and you can start now.

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2. Tally up your income. Once you've calculated expenses, determine how much your guaranteed income (e.g., a pension, annuity or Social Security) and variable income (e.g., part-time work or rental income) will cover. The remainder of your expenses will have to be funded by withdrawals from your investment portfolio.

3. Evaluate your Social Security options. You can start your Social Security benefits anywhere from age 62 to 70, but there are advantages to waiting. The earlier you start, the more your benefits will be reduced based on how many months you receive them before you reach full retirement age. If you wait until your full retirement age, your benefits won't be affected at all, and if you wait until after, your benefits will actually increase.

4. Fund the difference. The amount you withdraw from investments (either income or capital appreciation) should change a bit year to year, depending on how much your expenses and other income sources vary. It should also take into account market fluctuations and inflation adjustments.

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5. Set up a home base. With a variety of income sources, you'll have a mix of cash inflows on your hands. It will be easier to manage these from one "home base" account.

There are two approaches you can take to this. The simplest way is to use a single checking account to handle most, if not all, inflows and outflows.

However, if you'd like to mimic a real paycheck, consider setting up a linked checking and savings account. Have all of your retirement income deposited into savings, and then automate a semimonthly transfer to your checking account so that you get "paid"—just like when you were working.

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6. Have a safety-net fund. Aside from your investment portfolio and home-base account, you'll want to have a safety-net fund. Similar to the one you probably had when you were working, this is a reserve of investment funds that you can dip into when you need cash that your typical income doesn't cover.

This account could be key in covering larger, unexpected costs, such as a major medical expense or necessary home repair, and will sit separately from investments that you have specifically targeted for providing income in retirement.

7. Don't forget taxes. Given that employers typically withhold taxes from your paycheck for you, it's easy to forget about them once you stop working. In retirement, you'll be largely responsible for figuring out your own tax burden.

That said, you should set up a separate bank account so that you can transfer your estimated tax payments to it whenever you receive income that hasn't had any tax withheld, and work closely with an accountant at tax time. This will ensure that you don't spend anything that's not actually yours to keep.

—By Jon Stein, special to CNBC.com. Stein is founder and CEO of Betterment, which ranked 45th on the 2014 CNBC Disruptor 50 list. The firm offers Web-based money-management services.