Most retirees work their whole lives to become entitled to receive Social Security benefits. These retirement benefits can help cover costs in your later years once you're no longer earning a paycheck.

Unfortunately, Social Security benefit rules can be complicated, which can result in some retirees missing out on benefits they are entitled to. In fact, close to half of all Americans are confused about one specific aspect of Social Security that could end up leading to a very costly mistake. 

Here's what it is. 

Older couple talking with financial advisor.

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Almost half of all Americans aren't aware of a key Social Security rule

According to a recent survey conducted by Mass Mutual, just 54% of Americans can correctly answer a question about whether Social Security benefits continue to increase after the age of 70. And that's a big problem.

See, retirees often end up better off financially if they wait to claim their Social Security benefits until the age of 70. That's because those who have reached their full retirement age, or FRA (between 66 and 2 months and 67) can earn delayed retirement credits for every single month after FRA that they wait to claim their checks.

These delayed retirement credits ultimately raise your monthly checks by 8% for each year that you delay the start of your Social Security. They are the reason many retirees end up with more lifetime income if they claim benefits at the age of 70, rather than claiming it earlier.

But the trick is that these benefits can be earned only until age 70. And, unfortunately, the Mass Mutual data suggests that 46% of Americans incorrectly believe they can continue to increase their benefits by waiting longer than 70. 

For seniors laboring under this misconception, this could lead to a needless delay in claiming retirement benefits. And those who wait may never get back the money they gave up by delaying the start of their checks, as retroactive benefits are available only for a maximum of six months.

And those claiming spousal benefits could end up in an even worse situation if they don't understand the rules for earning delayed retirement credits. That's because those who are claiming spousal benefits on a husband or wife's work record actually cannot earn delayed retirement credits at all. So there's no reason to even wait until the age of 70. 

Don't miss out on Social Security benefits you're entitled to 

The last thing that you want to do is miss out on getting Social Security checks and not see a corresponding increase in benefits. And that's exactly what could happen if you wait to claim retirement or spousal benefits even though you aren't earning delayed retirement credits. 

To make sure that you're getting the money you're entitled to, it's important to understand how Social Security benefits work. And this means knowing the effect of claiming at different ages and considering all of the available techniques to maximize benefits so you can pick the best approach for you. 

If you aren't sure what the rules are, take some time to review Social Security guides, or consider talking with a financial advisor who can provide more insight into the best time to start your Social Security checks.