Apple employees celebrating the opening of the newest store in Brooklyn. Image source: Apple, Inc.

Saving up for retirement is so tough that most of us just avoid it. According to a 2013 study from the National Institute on Retirement Security, the average U.S. working household has just $3,000 saved, while those near retirement have just $12,000 put away.

In each case, most Americans have enough retirement cash to buy a 2006 Suzuki Forenza or fund nine years of morning cappuccino from Luke, the local barista who greets you like he was your bartender -- because he may as well be. (And you'll need someone with whom to drown your sorrows, right?)

Still, even if you're among the fortunate few who have a hefty retirement nest egg, you may still lack the capital you need to fund your golden years if you don't also have a plan to earn. Investing a portion of your savings in dividend stocks that pay out regularly can help fill the gap. Here are four such stocks to consider adding to your portfolio, presuming you don't already own them.

Apple -- a balance sheet like no other

For virtually any other company in the world, carrying $85 billion in debt would be a huge problem. Not for Apple (AAPL -2.15%). The iEmpire is so flush with liquid ($62.6 billion) and long-term ($169.8 billion) cash and investments that CEO Tim Cook could order the accounting team to wipe out all of the company's obligations tomorrow and have it be done in a few days, at most.

For retirement investors, Apple's cash position and prodigious cash flow from operations -- $63.2billion over the trailing 12 months, according to S&P Global Market Intelligence -- suggests that the company's 2.11% yielding dividend payout is not only safe, but should also continue to grow by 10% or more annually.

Coke's lineup of mini cans. Image source: Amy Sparks for The Coca-Cola Company.

Coca-Cola -- what's good for Buffett is good for you

Is there a product more addictive than Cherry Coke from Coca-Cola (KO -0.72%)? Not if you're Warren Buffett. In a Feb. 2015 interview, the octogenarian superinvestor told Fortune magazine that he drinks at least five 12-ounce servings daily. "I'm one-quarter Coca-Cola," writer Patricia Sellers quoted Buffett as saying at the time. To this day, his Berkshire Hathaway (BRK.A 0.37%) (BRK.B 0.29%) portfolio holds 9.27% of Coca-Cola's shares outstanding, good for roughly $16.84 billion in market value.

This year, Berkshire stands to be paid an estimated $560 million in dividends on its 400 million shares held. You wouldn't make nearly that much investing in your retirement portfolio, but you also shouldn't have to. At 3.31%, Coke's dividend yield is higher than the historically average rate of inflation (3%). That alone should make buying the stock worthwhile. Mix in a long history of management boosting Coca-Cola's annual payout by at least 8% per share and you've the equity equivalent of an ATM machine.

Microsoft put plenty of marketing muscle into Windows 10 -- and for good reason. Image source: Microsoft.

Microsoft -- still essential

Do me a favor: Count the number of times someone has threatened to permanently disrupt Microsoft's (MSFT -0.14%) business. Netscape gave it a go in the early '90s, only to be driven to the verge of bankruptcy and into the arms of AOL by the end of the decade. Federal regulators took a shot at splitting the company in 2000 only to see their efforts thwarted on appeal, leading to a settlement. Later, cloud computing threatened to reduce or even eliminate users' reliance on PCs and the Windows operating system.

Microsoft is still standing in spite of it all, generating $85.3 billion in fiscal 2016 revenue. Over $40 billion of that is derived from sales in the More Personal Computing group that's responsible for sales of Windows licenses.

Between old and omnipresent products like Windows and Office and newer efforts such as the Surface tablet, Microsoft produces over $30 billion in annual cash from operations, more than enough to satisfy its capital expenditures and still pay a dividend that yields 2.55% as of this writing, and that has grown by 17.6% annually over the past five years, S&P Global Market Intelligence reports.

Image source: Toyota.

Toyota -- clean machines create brand goodwill

Among the world's largest automakers, only Toyota (TM 0.21%) cracks Interbrand's list of the 10 most valuable brands. The carmaker saw its brand value jump 16% last year on the strength of its efforts in clean driving, led by the Prius. Since first rolling off the line in 1997, Toyota has sold over 8 million hybrid vehicles around the world. No other carmaker has as good a reputation with environmentally sensitive drivers.

Retirees should be equally interested, even if they don't share the same concern for the planet. Toyota stock trading on the NYSE yields 3.07% as of this writing, while ongoing investment in the per-share payout -- up 33.2% annually over the last five years -- should give current investors plenty of spending money for their later years.

Start early if you can, but start regardless

Whether you add one, none, or all four of these stocks to your retirement portfolio, the key move for you as an investor is to act. Look to buy shares of businesses with durable franchises, big brand names, and a long history of paying and growing their dividends. Like Apple, Coca-Cola, Microsoft, and Toyota, they'll be the ones that keep sending you cash long after you've bought shares.

And -- you won't have to dress in a suit and tie, go to the office, or tip Luke the barista in order to collect. Isn't that what we all want out of retirement?