Spousal and survivors' benefits are a key part of Social Security. But getting remarried after divorce or a spouse's death can take away your hard-earned benefits.

In the latest installment of our Social Security Q&A video series, Dan Caplinger, The Motley Fool's director of investment planning, takes a question from Miriam, who notes that her first husband died when she was 51, after which she remarried at 55 and is now 60. She wants to know what benefits she's entitled to. Dan notes that widow's benefits can start at age 60, but if you get remarried before age 60, those benefits aren't available. If a widow waits until after age 60 to remarry, however, the widow's benefits are preserved. Dan further points out, though, that you're allowed to start taking spousal benefits based on your new spouse's work history as soon as a year after you get remarried, but unlike widow's benefits, those spousal benefits don't kick in until age 62. Dan concludes that remarriage can be a touchy subject with Social Security but that it's essential to know all the rules that can apply.