More Americans are getting the message when it comes to claiming Social Security benefits.

The number of near-retirement workers planning to take Social Security benefits as soon as possible has fallen sharply, according to a new survey by Fidelity Investments. Just 28 percent of 61-year-olds say they plan to file for their benefits at age 62 — the first year of eligibility. In 2008, 45 percent planned to file at 62.

An improved economy is one key reason for the changed attitude about claiming. But it may also reflect heightened public awareness of the challenges posed by rising longevity.

For many households, Social Security is the only source of guaranteed lifetime income, and delayed filing can boost that income significantly. Benefits are calculated using a formula called the Primary Insurance Amount (PIA). Although you can claim benefits as early as 62, by waiting until your full retirement age (currently 66), you will receive 100 percent of PIA.

Every 12 months that you delay beyond that point, until age 70, tacks on an additional 8 percent.

The PIA formula is designed to be "actuarially fair," meaning all claimants should come out roughly equal no matter when they claim. But delayed filing often works out in favor of those who are patient — especially for better-educated, healthier households.

Among U.S. women with average health, 31 percent will live to 90, and 12 percent will make it to 95, according to Social Security Administration mortality data. Among women whose health is better than average, 42 percent will live to 90, and 21 percent will survive to 95.

Married couples have significant opportunities to maximize household benefits by coordinating their claims.

A growing number of financial planners are learning to advise clients on Social Security claiming. And online software tools can be very useful in identifying a strategy. Several companies offer help for a small fee that often comes with a one-on-one consultation.

Fidelity introduced a robust Social Security analytics tool for customers two years ago.

This month, it launched a free tool that provides a basic illustration of the likely variations in lifetime and monthly benefits at various claiming ages.

No matter where you seek help, the baseline information you will need is contained in the annual statement that the SSA prepares for you.

You can always access your statement — and download it as a PDF file — by creating a My Social Security account on the SSA website.

Mark Miller writes for Reuters.