Social Security is a key part of your financial security in retirement, but it's also complicated. In particular, dealing with the complex rules that govern benefits for married couples can take a lot of specialized knowledge.

In the following video, Dan Caplinger, The Motley Fool's director of investment planning, goes through three rules you should know about benefits for married couples. First, Dan notes that if you're just getting married, you have to wait a year before claiming spousal benefits based on your new spouse's work history. To claim survivors' benefits, couples have to be married for nine months before the date of death, although exceptions apply for accidental death or for members of the military who die in the line of duty. Finally, Dan goes through the rules for divorced spouses, noting that you have to have been married for at least 10 years to claim benefits on an ex-spouse's work history. Dan concludes that even though Social Security is a tricky program, it's worth spending the time to understand its rules.