So, you're getting ready to retire soon. That's great news! But, do you have a solid plan for where your income will come from? Social Security is likely a big part of that plan, if you're like most pre-retirees. That means it makes sense to maximize your Social Security benefits -- or at least understand how these benefits work. 

However, despite the fact that Social Security is an essential source of retirement funds, a great many pre-retirees who will soon be relying in the program aren't clear on some key Social Security facts. In fact, many older Americans not only don't know the rules for Social Security, they also have some inaccurate ideas that could end up costing them.

To make sure you know the truth and don't have your retirement derailed by low Social Security benefits because you made claiming decisions based on inaccurate info, here's the reality about some common misconceptions pre-retirees harbor.

Older couple with calculator and financial paperwork.

Image source: Getty Images.

You'll probably claim Social Security before you plan to

Many people plan to claim Social Security late in their lifetimes, rather than when they first become eligible for benefits. Waiting to claim can make sense because you'll get bigger benefits if you delay -- although you'll have to do some simple math to make sure waiting is financially sound.  

The problem is, you're unlikely to be able to continue working as long as you want to. In fact, according to a recent study conducted by Nationwide, future retirees on average anticipate claiming Social Security four years later than the age at which most recent retirees filed for benefits. While 66 is the age most people think they'll retire, the reality is they go at 62. If you retire at 62 when 67 is your full retirement age -- the age at which you receive your standard benefit -- you'll see as much as a 30% reduction in the monthly income you'd have received. 

Of course, many pre-retirees may not understand how big the impact is of retiring so early, as just one in three pre-retirees know their full retirement age and only 12% know the factors that control how much of their benefits they'll obtain.

To  make sure you understand how Social Security benefits are calculated, check out this Complete Guide to Social Security. And, to make certain you're prepared if you need to retire earlier than expected, consider trying to step up your savings -- you can take advantage of catch-up contributions to IRAs or 401(k)s if you're over 50. You can also explore whether it makes sense to take Social Security Disability instead of retirement benefits if your health necessitates leaving the workforce before you planned.

You'll spend more of your Social Security on healthcare than you expect

Pre-retirees generally anticipate they'll spend 15% of their Social Security benefits on healthcare, although four in 10 people getting ready to retire anticipate that none of their Social Security will be used to cover care costs. In reality, Nationwide reports that someone who retired at 62 might spend an average of 64% of Social Security income tending to health needs. 

Unfortunately, healthcare costs come as a major shock to most retirees, especially as medical issues often develop much earlier in retirement than anticipated. As many as 80% of current retirees indicate health problems developed sooner than they expected. Further, almost two in five retirees say their health problems are interfering with retirement plans.

Preparing for serious health issues is hard. Consider investing money in a health savings account (HSA) during your working life and leaving the money to grow. You can make tax-free contributions and take money out tax-free if you use it for covered health expenditures, or can withdraw money for any purpose after age 65 -- although you'd pay taxes on withdrawals if the money isn't for care. You'll be eligible to make HSA contributions if you have a qualifying high deductible health plan. 

Your benefits are going to be smaller than you think 

Social Security benefits are based on a formula that adjusts your wages over your career for inflation and determines an average wage based on your highest 35 years of earnings. 

Most people don't understand how the formula works, and don't have any idea what their benefits will be. Unfortunately, pre-retirees tend to overestimate, rather than underestimate, how generous Social Security benefits are. In fact, as Nationwide explains, future retirees anticipate they will collect close to 30% more from the Social Security Administration than the benefits current retirees are actually pocketing. 

You can find out how much your anticipated benefits will be at age 62, at full retirement age, and at age 70, by checking your online Social Security account. If you plan to retire at a different age, this article explains how to calculate how much your benefits will be reduced or increased by retiring earlier or later. 

The main way to plan for smaller benefits is to save more money to make up the shortfall in income. Although, you do want to make sure you're getting the maximum benefit available. This can mean taking steps such as determining if you can claim Social Security on a spouse's account or if delaying claiming benefits makes sense. 

Don't let your retirement security suffer due to Social Security surprises

After working hard throughout your life, you deserve to retire with dignity and not spend your golden years worried that your Social Security check won't stretch far enough. Make sure you calculate ASAP how much income you'll need during retirement -- and find out how much of it Social Security will realistically provide -- so you can make a comprehensive savings plan.

The Motley Fool has a disclosure policy.