Seniors who want to collect Social Security have an eight-year window to start claiming benefits. That period begins at age 62 and lasts all the way until 70. (Technically, you don't have to file at 70, but as we'll get into in a minute, there's no reason to delay beyond that point.)Smack in the middle of that eight-year window is full retirement age, otherwise known as the age at which you're allowed to collect the full monthly benefits your work history entitles you to.