Source: Wikimedia Commons.

Social Security is a key part of how millions of retirees make ends meet financially. But there are several things about the Social Security program that just aren't fair, and those shortcomings make many people critical of whether Social Security reform is necessary.

In the following video, Dan Caplinger, The Motley Fool's director of investment planning, looks at three ways that Social Security is unfair. He notes that the amount of Social Security benefits you get isn't always directly proportional to the taxes you pay, with higher-income workers getting a smaller percentage of the taxes they pay back in benefits. Second, Social Security favors married couples, giving spousal and survivors' benefits that most single people don't take advantage of. Finally, for some people, Social Security benefits are subject to income tax, which many retirees see as double taxation on their career earnings. Social Security might not be fair, but it's still a lifeline for millions of retirees in America, and it's unlikely to go away.