71% of Americans Don’t Know This Critical Fact About Social Security

What is the full retirement age for the purposes of Social Security benefits?

A recent survey by Massachusetts Mutual Life Insurance Company (MassMutual) found that nearly three quarters of respondents reported incorrectly that the answer is 65.

The correct answer is: it depends.

Your full retirement age for the purposes of Social Security retirement benefits depends on your birth year. For people born in 1937 or earlier, it is in fact 65. But if you were born after that, then it's somewhere between 65 and 67.

Source: Social Security Administration, Retirement Planner: Full Retirement Age.

"Perhaps the greatest Social Security deficit in this country is the lack of education around the retirement benefits of the program," said Michael R. Fanning, an executive vice president at MassMutual. "With millions of Americans nearing retirement each year, many may be at risk of underutilizing a critical component of their retirement income stream."

In no case is this truer than when it comes to knowing one's full retirement age, which is a central tenet of the Social Security system. This number not only factors into when a person can claim their benefits -- it also impacts the size of one's monthly check.

A person's full retirement age is the age at which they're eligible to receive their primary insurance amount -- that is, their full Social Security benefits based on their 35 highest-earning working years.

You can take benefits before then, as early as the age of 62, but they'll be reduced to reflect the fact that, by doing so, you'll receive more checks than someone who takes them later. If you take them at 62, for instance, then your check will be approximately 25% less than your primary insurance amount.

Alternatively, you can wait to take benefits even after you've reached your full retirement age, with the payoff being a larger monthly check. If you delay receiving benefits until turning 70, for instance, your checks could be as much as 32% larger than your primary insurance amount.

In short, your full retirement age is among the most important things to know when planning for life after work. With a growing share of Americans relying on Social Security benefits to fund their retirements, getting every penny out of the system is now more critical than ever.