Unless you're living under a rock, you've surely noticed the controversy over gay marriages that has inspired passionate support and opposition across America. It's a legal issue -- and a societal one. And in many ways, a religious and ethical one, too. But perhaps you haven't realized that it also has some serious implications for the world of business and investing.

Most employers offer their workers benefits. These might be paltry, such as a free lunch now and then, or they may be quite generous, including health insurance, matching funds for retirement plans, life and disability insurance, and more. Some benefits, such as health insurance, are also commonly offered to spouses of employees. According to the Society for Human Resource Management, as of 2003 some 30% of companies offered benefits to opposite-sex domestic partners of employees. About 23% did so to same-sex domestic partners -- which amounts to some 7,000 U.S. employers, including about half of all large companies. Some such companies include Boeing (NYSE:BA), Washington Mutual (NYSE:WM), Microsoft (NASDAQ:MSFT), Coca-Cola (NYSE:KO), UPS (NYSE:UPS), and Starbucks (NASDAQ:SBUX).

Now that gay marriages are happening in greater numbers than before, with the possibility that they could be widely recognized as legal in the near future, businesses are suddenly having to do some soul-searching -- or budget-searching. They have to decide whether to extend their current benefit mix to all spouses, including same-sex ones, or perhaps whether to change their current benefit offerings for all employees. Many employers may find that they're ultimately required to make certain changes to their current policies.

As you know, health insurance isn't cheap. It's a controversial topic on its own, as more and more employers and employees are finding the costs unbearable. Given that, if employers extend benefits to same-sex spouses, it will take a financial toll of some sort simply because more people will be covered. To offset this, some firms may end up reducing or eliminating benefits offered to unmarried domestic partners, whether same-sex or opposite-sex.

There is likely to be a lot of gray area surrounding this issue. For example, if a gay employee gets married out-of-state and then returns to work in a state where gay unions are not recognized, should the company extend spousal benefits? (Even if the law says no, some companies may want to do so anyway, just as many benefits offered by companies are not required by law.)

If companies end up with greater benefits costs, these would likely be passed on to customers via higher prices for goods and services, and/or they would simply put pressure on the firms' bottom-line profits. That said, it remains to be seen what the net expense changes turn out to be. What seems likely, though, is that many companies will end up either increasing or decreasing the range of their benefits packages.

In the meantime, maximize your personal financial situation by learning more about how to manage your own benefits in our Insurance Center and Retirement Center.

Longtime Fool contributor Selena Maranjian owns shares of Microsoft, has ridden on Boeing planes, and enjoys an occasional mocha Frappuccino.