Michael Kitces writes about the social security file-and-suspend strategy.   His article begins as follows:

The Social Security file-and-suspend strategy has been used primarily for couples to coordinate the delay of individual retirement benefits earning delayed retirement credits while making a spouse eligible to begin his/her spousal benefits. It can also be used as a partial form of “undo” for a retiree who started benefits early, and later wishes to suspend them at full retirement age to earn delayed retirement credits a benefits increase that can partially or fully offset the decrease triggered by electing benefits early in the first place.

However, the strategy to file and suspend can also be used as a proactive planning strategy for individuals, because it creates an opportunity for the retiree to subsequently “undo” the decision to delay and “retroactively” claim benefits back to the date they chose to file and suspend e.g., full retirement age. Thus, for someone who is approaching age 66 and isnt certain about whether its a good idea to delay or not, choosing to file and suspend allows them to wait until age 70 to make the final decision, enjoying the benefits of the delay if it still makes sense to do so, but having the opportunity to go back and claim benefits at 66 if theres a change in health or circumstances.

To read the full article see Why Individuals Should File And Suspend Their Social Security Benefits – Reinstatement Of Voluntary Suspension Versus Retroactive Benefits | Kitces.com.

http://www.irs.gov/irm/part4/irm_04-025-010.html