Social Security plays a major role in the retirement finances of tens of millions of Americans. Roughly 90% of people 65 and over are already collecting benefits through the program, and for 50% of married couples and 70% of single retirees, those checks provide at least half of their retirement income.

Americans are eligible to start claiming benefits as soon as they turn 62. But if your 62nd birthday will arrive in 2021, there's one important change you need to know before you file for Social Security.

Senior couple standing in the kitchen drinking coffee

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How your age will affect your Social Security benefit amount

First, a bit of background. The age you are when you file for benefits has a direct impact on the size of your monthly checks. To receive the full benefit amount you're entitled to, you have to claim at what the government designates as your full retirement age (FRA).

For those who turned 62 last year, the FRA was 66 years and 8 months. However, the FRA is increasing by 2 months this year -- as it has every year since 2017. So if your 62nd birthday is in 2021, you'll have an FRA of 66 years and 10 months.

Obviously, this means that to receive your full benefits, you'd need to wait a couple of months longer to begin claiming. But more than 6 in 10 seniors don't wait that long, and if you claim Social Security early, the increase in FRA means your benefit reductions for doing so will be greater.

Consider this: Someone with an FRA of 66 years and 8 months who chose to claim benefits at 62 would see their check size reduced by 28.3%. If you have an FRA of 66 years and 10 months, though, and claim at 62, your benefits will be reduced by 29.2%. That may not seem like a big difference, but it could potentially amount to a few hundred dollars a year.

Strategies that can boost your benefits

You don't have any control over your FRA because it's based on the year you were born. However, you can take steps to increase the amount of Social Security benefits you collect each month.

One option is to wait a little longer to file for Social Security. Holding off on claiming until you reach your FRA will ensure you receive your full benefit amount, but waiting beyond that age will boost the size of your checks even further. If you have an FRA of 66 years and 10 months and you wait until age 70 to claim, you'll receive 125.3% of your full benefit amount. That could result in hundreds of dollars more per month than you'd get if you claimed at or before your FRA.

Additionally, if you want to receive as much as possible from Social Security, make sure you've worked during at least 35 years before you begin taking benefits. The Social Security Administration uses the 35 highest-earning years of your career when it runs the calculation upon which your benefits are based. If you earned paychecks in fewer years than that, the government will be factoring some zeros into that math, which will reduce the size of your monthly checks.

Tens of millions of retirees depend on Social Security to help make ends meet. If you expect your benefits to be a substantial source of income in retirement, it pays to do your homework before you begin claiming them. Making sure you know your FRA and how it will affect your benefits is just one way to help ensure you're heading into your senior years as prepared as possible.