If you are in your 40s or 50s, and already have your 62nd birthday highlighted on the calendar with a big smiley face, here’s some advice: check your math first.

Age 62 is when Social Security payments first become available to most of us. However, full benefits don’t kick in until 66 for current retirees, and 67 if you were born after 1959. There are two reasons to consider waiting. One, taking the money now puts less in your pocket later. Let’s take a 62-year-old woman who retires this year and qualifies for $9,000 annually. She will get $12,000 if she waits until her full retirement age of 66, and $15,840 if she waits until 70. If our 62-year-old takes the money now, her grand total will be greater for about 12 years than if she waited until 66. At age 74 in this case, she begins to fall behind. Keep in mind that Social Security is adjusted for inflation annually.

Secondly, if you remain in the workforce between 62 and your full retirement age, your income may take a big chunk out of Social Security. If our same 62-year-old takes Social Security but continues working, she could earn $14,160 from her job this year and still keep her $9,000 in Social Security payouts. For every $2 she earns above $14,160, however, she forfeits $1 of her Social Security until she hits full retirement age.

Patience may be a virtue, but there are reasons why more than 70% of retirees take Social Security before their full retirement age. Some really need the money. Some figure that Social Security benefits will dwindle, given the nation’s debt load. And some figure they might not live long enough to enjoy the money in their mid-70s, when waiting finally pays off.

“Choosing when to retire is an important decision, but it’s also a personal choice and one you should carefully consider,” says Martina Dunkerson, Social Security Administration public affairs specialist for southern Indiana. She suggests you go to the Social Security website at http://www.socialsecurity.gov/pubs/10147.html to help make that big decision: whether the smiley face stays or goes.