Collecting Social Security at age 62 cuts your annual benefit by about 25% compared with what you'd get if you waited until full retirement age - that's 66 if you were born from 1943 to 1959, or 67 ir you were born in 1960 or later. To do the math, you need to consider whether you expect to live a long life.

Say you've just turned 62 and qualify for $17,280 a year now or $23,772 at 66 (in today's dollars). Start early and you'll have collect $69,120 by the time you reach 66. Wait, and higher payments will make up for those missed years in 10-1/2 years. If you live until at least 76-1/2, postponing your benefits was worthwhile. The odds are in your favor: According to the Social Security Administration, the typical 62-year-old man should live until 80-1/2, while the life expectancy for a 62-year-old woman is 83-1/2.

When you collect a Social Security check at 62, that's $17,280 you won't have to withdraw from your IRA. Add in the extra tax-deferred growth (assuming 5% returns), and your break-even point moves out by three years - to age 79-1/2. Even then, odds are you'll live that long.

The math can get even more complicated if you're married. According to new research from Boston College's Center for Retirement Research, the best strategy for many couples is for the wife to take Social Security at 62 and the husband to wait. The reason is that men, on average, earn more and die younger. In this scenario, a wife would take her benefit at 62 and inherit her husband's larger check later.

Finally, waiting to take Social Security assumes you can. Surveys show that 40% of retirees are forced into early retirement, through either downsizing or health issues.