You're certainly right that none of us know how long we will live. We make our retirement income choices framed by two desires. The first is to maximize our income while living. The second is to make the best bet we can on how long we will live. We do that by playing the odds.
The best candidate for delaying taking Social Security benefits is a married man with a younger wife. In his case, the odds favor a long payout of benefits even if he dies relatively young because his surviving spouse will receive a higher survivor benefit. (This assumes that his earnings record and benefit will be materially higher then hers so her survivor benefit will increase upon his death.)
While a 65 year old male has a 63 percent chance of surviving to 80 and only a 20 percent chance of surviving to 90, there is an 89 percent chance he OR his spouse will survive to 80 and a 45 percent chance one of them will survive to 90.
The second best candidate for delaying taking Social Security benefits is a single woman. She is likely to benefit because women have relatively long life expectancies.
Single men come in third. They should consider delay if they are relatively healthy, avoid delay if they are unhealthy.
Married women are the best candidates for taking benefits early, not because they have short life expectancies but because their long term benefit is likely to be a higher survivors benefit based on their husbands' earning record.
Again, lest someone accuse me of being a nasty old sexist, all of this is based on two things. First, that women live longer than men and, second, that women tend to have lower earnings than men. Given the changes in women attending college vs. men, this may change dramatically over the next 20 years.
Search the website for Social Security and you'll find a lot more on this subject, including a link to a Center for Retirement Research Study that was my source.
Scott
