There are certain programs retirees tend to be dependent on. One important one is Social Security.

Even though workers are encouraged to set money aside for retirement, seniors often end up getting the bulk of their income from Social Security. And when it comes to healthcare in retirement, a related but separate program comes into play -- Medicare.

Unfortunately, though, many workers feel they're in the dark about Medicare. A good 44%, in fact, say they're not getting enough education about this key program, according to a recent Bank of America report. If you're in that camp, here are some key points about Medicare you should know.

A person at a desk taking notes.

Image source: Getty Images.

1. Medicare isn't free

It's a big misconception that once you sign up for Medicare, all of your healthcare needs will be covered in full, and that you won't have to spend any money on medical costs. That couldn't be further from the truth.

First of all, it costs money just to be a Medicare enrollee. Though Part A, which covers hospital care, is generally premium-free, Part B, which covers outpatient services, costs money to sign up (the same way you may be used to paying ongoing premiums for private health insurance). And if you stick to original Medicare, as opposed to Medicare Advantage, you'll also pay a premium for Part D, your drug plan.

Then there are copays, coinsurance, and deductibles to think about. Medicare Part A may not charge a premium, but if you wind up in the hospital, you'll pay a deductible for your initial stay. And when you use Part B, you'll be responsible for a portion of your care in the form of coinsurance. These are all costs you'll need to plan and save for so you don't wind up cash-strapped in retirement (or, worse yet, being forced to skimp on care).

2. There are some services Medicare won't pay for

Medicare might pay for you to see the doctor for a bad cough or get an MRI if you've been having dizzy spells. But it won't pay for you to get your teeth cleaned or get your eyes checked to see if you need a new eyeglasses prescription.

It often comes as a shock to seniors to learn that original Medicare won't cover dental, vision, or hearing services. But Medicare Advantage, an alternative to original Medicare, generally will.

However, Medicare Advantage isn't right for everyone. Depending on where you live, you may not be able to find a plan you're happy with, or one that's affordable for you. As such, it's important to understand Medicare's limitations -- and save money ahead of retirement so you're able to cover all of your healthcare needs.

3. The cost of Medicare will hinge on your plan choices and income

Medicare Part B charges enrollees a standard monthly premium. But you might end up paying a surcharge for Part B if you're a higher earner. Meanwhile, the amount you spend on Part D will depend on the plan you choose, and also, what your income looks like.

Then there's Medicare Advantage. The amount you pay for coverage will depend on the Advantage plan you choose. But all told, don't think that all seniors pay a universal monthly premium for their Medicare coverage.

There's lots to know

Medicare is a complex program with lots of rules, just like Social Security. And it's important to know a fair amount about it before you're at an age where you're eligible to enroll.

If you feel you lack Medicare education, start reading up on how it works. That should put you in a better position to plan and save for your future healthcare needs.