Social Security's rules are complex, but often, they reward those who are able to defer taking their benefits beyond their full retirement age. But that isn't true of all Social Security benefits. With some, there's no advantage to be gained by waiting.

In the following video, Dan Caplinger, The Motley Fool's director of investment planning, goes through two situations where waiting for benefits won't do any good. Dan explains how delayed credits generally allow you to get bigger monthly checks by waiting as long as age 70 to start taking benefits. But Dan notes that with spousal benefits, there are no delayed credits for waiting past full retirement age, so there's no reason to wait until after then. Moreover, Dan talks about how a similar rule applies to survivors' benefits after a spouse has passed away, although he notes that you shouldn't confuse this with the choice that spouse makes about when to take his or her own benefits before death. Dan concludes that you have to know the rules to make sure you don't needlessly waste months of benefits you could have received.