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FAASF stands for file as a spouse first. In doing so, a spouse can file for his or her spousal benefit until age 70, when their own benefit will likely have grown (since you didn't draw against your earnings record for benefits yet).
This is just one of a number of Social Security filing options available to claim benefits. This one, FAASF, can produce the largest return, since the spousal deferral likely grows substantially to age 70. Factors like health and other issues make the decision unique to each, but this one can generate the largest total return from Social Security.
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