Gayle B. Ronan • E-mail

In mid-October Kathleen Casey-Kirschling, a retired Maryland teacher, became the first baby boomer to file for Social Security benefits. Over the next two decades nearly 80 million more will follow after answering the same question she did: Should I file for benefits sooner rather than later?

Casey-Kirschling, who turns 62 on Jan. 1, chose sooner.

Most people take their benefits before reaching their full retirement age, according to the Social Security Administration. About 50 percent file at the earliest possible date, three months prior to turning age 62, which is what Casey-Kirschling did.

While ‘sooner’ is a popular choice, it is not always the right choice, especially in the face of increasing life spans, says Michael Astrue, commissioner of Social Security.

The reason? It reduces the monthly benefit for the rest of the filer’s life. Given a long enough life — extending into one’s 80s or beyond, for instance — not waiting for full retirement benefits produces a smaller total payout. This could be especially harmful to those who may have undersaved for retirement and lack other sources of income, such as a pension to see them through.

The early benefits choice is also more punishing than it used to be.

Interactive Retirement calculator Fill in your information and see if you're saving enough to make it comfortably through your retirement years.

Previous generations attained their full-benefits at age 65. However, it will be 66 for those born in 1954 or earlier and gradually increases to 67 for those born in 1960 or later.

Previously a person whose full retirement age was 65 would have received 80 percent of their full benefit if they filed at age 62. Today’s 62 year-old will only receive 75 percent of their benefit. For someone entitled to full benefits at age 67 the reduction will fall to 70 percent if taken at the earliest possible date.

Spousal benefits are even more severely impacted by early filing. Filing at 62 used to reduce them by 25 percent, now they will be lowered by 30 percent and ultimately by 35 percent.

“People tend not to make the filing decision rationally,” says Alicia Munnell, director of the Center for Retirement Research at Boston College. “They just grab their benefits without thinking about how filing early will affect them down the road or about how the surviving spouse, typically the wife, will then have to live off a potentially reduced benefit the rest of her life.”

Yet for some ‘sooner’ can make sense.

“Obviously [sooner is for] those where pure financial need is a factor,” answers Dan DeKeizer, a vice president and actuary with MetLife Retirement Strategies Group in New York. “Many of us, however, are either still able to work or have other sources of income to meet our living expenses until we reach 66.” Also, for those still working, benefits are reduced at a rate of $1 for every $2 earned over $12,960 in 2007. For many in their 60s and still working full-time, the reduction makes filing pointless, wiping out their benefit.

“We start our retirement planning consultations with clients by asking about their health,” says Lisa Kirchenbauer, a certified financial planner with Kirchenbauer Financial Management & Consulting in Arlington, Va. “If they have any health [or longevity] issues, they probably are better off taking benefits sooner rather than later.”

MORE FROM TECHNOLOGY & MONEY

Technology & Money Section Front

What a mess! 5 financial cleanup tips Heavy load? Best backpacks for kids Money 911: What’s your emergency? Pinching pennies like your grandparents Pinching pennies like your grandparents Mattel awarded $100 million in Bratz lawsuit A good find: GPS to locate the kids Survive the drive! Great gear for kids Need some cash? Don’t raid your savings The PC gets more personalized Technology & Money Section Front   Add Technology & Money headlines to your news reader: