Piper's calculator, Open Social Security, is free but doesn't account for child benefits. (When you file for the checks, some people in your family might also qualify for benefits.)
Kotlikoff's software company has its own calculator, called Maximize My Social Security, which costs $40 a year. The tool will tell you which claiming strategy will result in the highest lifetime benefits. Kotlikoff estimates that up to 70 percent of people should wait until 70 to file, although less than 5 percent of people do.
"You want answers from economists," he said.
Social Security Administration: The SSA itself remains the best place to receive information about Social Security, said Nancy Altman, president of Social Security Works.
"In addition to having a nationwide system of local offices where people can make appointments and a [toll-free] number with trained workers, SSA also has online calculators and a lot of relatively easy to understand fact sheets explaining the various rules and options," Altman said.
Once you've done your own research and settled on a claiming strategy, then consult with the Social Security Administration, said Ed Slott, an expert on retirement saving.
"Many of the options you choose may be irrevocable," he said. "You basically have one chance to get it right."
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