Many investors rely on dividends from their investments to provide much-needed income. But companies aren't always allowed to continue making dividend payments. If a company no longer has any retained earnings on its balance sheet, then it typically can't pay dividends except in extraordinary circumstances.

What retained earnings are
Retained earnings represent the accumulated earnings from a company since its formation. Most companies lose money when they first start up, and so for a time, their retained earnings will be negative. That's one reason why most start-ups don't pay dividends, in addition to the fact that new companies generally need to hold onto any cash they have to grow their business.

Once a company starts making money, then its retained earnings start to rise. Once the company has made up for any earlier losses, a positive balance in its retained earnings will allow it to pay dividends if it chooses.

Why companies can pay dividends even when they're losing money
Many investors find it confusing that a company can pay a dividend even when it's losing money. The reason is that when a company retains earnings from previous profitable periods, it effectively reserves the right to pay them out to shareholders as dividends in the future. Therefore, most dividend-paying stocks don't have to suspend their dividends when they hit a temporary setback that causes them to lose money, because they've already built up a reserve of retained earnings to draw from.

Of course, just because a company can pay dividends doesn't mean it always will. The company won't always have actual cash to pay a dividend, even if the retained earnings line item on its balance sheet is positive. Still, some companies will borrow money specifically to pay a dividend during times of financial stress.

Finally, there is one situation in which a company can pay a dividend even with negative retained earnings. If the company is wrapping up its operations, then it can make dissolution or liquidation dividend payments to shareholders regardless of the condition of its balance sheet.

Still, in the vast majority of cases, companies can't pay dividends that exceed their retained earnings. Dividend investors should therefore keep an eye on the balance sheets of the companies whose stock they own to get an early warning of any potential problem with paying dividends in the future.

Do you like dividend stocks? Focusing on stocks that pay you back is just one of many investing styles. If you're ready to take the next step on your investing journey, head on over to our Broker Center. We have plenty of resources to help you get started.

This article is part of The Motley Fool's Knowledge Center, which was created based on the collected wisdom of a fantastic community of investors. We'd love to hear your questions, thoughts, and opinions on the Knowledge Center in general or this page in particular. Your input will help us help the world invest, better! Email us at knowledgecenter@fool.com. Thanks -- and Fool on!

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.