Social Security benefits are an important part of retirement, and yet the vast majority of workers don't fully understand how they work. In fact, a whopping 91% of workers age 50 and older say they don't know how their benefit amount is calculated, a survey from Nationwide revealed.

Although Social Security can be complex, it's not as confusing as you might think. And the more you understand about how the program works, the better choices you can make to maximize your benefits. If you want to receive the most money possible from Social Security, make sure you're avoiding these three mistakes.

Older couple sitting at a table looking worried.

Image source: Getty Images.

1. Not working a full 35 years

Your basic benefit amount is based on an average of your 35 highest-earning working years. So if you don't work a full 35 years, you'll have zeros added into your average to account for the years you weren't working. That lowers your average, which, in turn, also lowers your benefit amount.

If you want to boost your benefits, one way to do that is to work more than 35 years. There's a good chance you're earning a much higher salary now than when you first started your career, so by working longer now, you can replace some of those lower-earning years from your 20s with more current, higher-earning years. That will result in a higher earnings average as well as fatter monthly checks.

Some people may not want to work longer than they have to, however, so another way to boost your basic benefit amount is to simply increase your income now. Picking up a side hustle can make it easier to save more for retirement, and the extra income will also increase your earnings average and result in more money in benefits.

2. Claiming at the wrong age

Even if you work hard to increase your basic benefit amount, you might undo all that effort by claiming benefits at the wrong age. To receive the full amount you're entitled to, you'll need to wait until your full retirement age (FRA) to claim. If you were born in 1960 or later, your FRA is 67 years old. If you were born before 1960, your FRA is either 66 or 66 and a few months.

If you claim before your FRA, your benefits will be reduced -- up to 30% if you have an FRA of 67 and claim at age 62. But if you wait until after your FRA to claim, you'll receive bigger checks each month -- up to 32% more on top of your full benefit amount if you have an FRA of 66 and claim at age 70.

In theory, it shouldn't matter at what age you claim, because your benefits should even out over a lifetime. If you claim early, your checks will be smaller, but you'll receive more of them. If you wait, you'll receive fewer checks, but they'll be bigger. So if you live an average life span, you should receive roughly the same amount regardless of when you claim. However, life doesn't always work out so cleanly, and sometimes there is a definite advantage to claiming at one age over another.

The biggest factor to consider is life expectancy. The average 65-year-old can expect to live until around age 85, according to the Social Security Administration. If you have an average life expectancy, it might not matter when you claim benefits. But if you end up living longer than average, you'll likely come out ahead by delaying benefits. On the other hand, if you have reason to believe you'll live a shorter-than-average lifespan, you may be better off claiming earlier so you can enjoy your money for as long as possible.

3. Not applying for all the different types of benefits you might be entitled to

When it comes to Social Security, most people are familiar with the standard retirement benefit. As long as you've worked and paid Social Security taxes for at least 10 years, you're eligible to collect this type of benefit. But that's not the only type of benefit you could be entitled to receive.

There are also spousal benefits, survivors benefits, and divorce benefits, for example. Even if you've never worked a day in your life, you might still be able to collect benefits based on a spouse's or former spouse's work record.

The eligibility requirements vary for each benefit type, but if you're currently married, divorced, or widowed, it's worth looking into these types of benefits to see if your situation fits the bill. The Social Security Administration typically won't notify you if you're eligible, so it's up to you to make sure you're receiving all the types of benefits you're entitled to.

When you don't know the types of benefits you're eligible to receive or how your benefit amount is calculated, you could unknowingly be missing out on more money. But a little bit of knowledge can go a long way, and the more you understand about Social Security benefits, the better decisions you'll be able to make to ensure you're receiving the most money possible.