Tens of millions of Americans are on Medicare, and millions more become eligible every year. If you expect to join Medicare in 2018, it's important to have the information you need to make smart decisions about this vital healthcare coverage. To help you with that, this simple guide gives you the ins and outs of Medicare and what you need to know in order to make the most of it.

How to get Medicare

The federal government has made getting Medicare as simple as possible. The process is automatic for many people, including most of those who receive Social Security benefits at least four months before their 65th birthday. Medicare will assume that you want both Part A hospital coverage and Part B medical coverage if you qualify for automatic enrollment, and so you'll need to contact them directly if that's not the case.

Even for those who aren't automatically enrolled, an online application for Medicare is available from the Social Security Administration website. You can choose to apply for Medicare only or to apply for both Social Security and Medicare at the same time. If you prefer, you can call the SSA or visit a Social Security office in your area to sign up for Medicare. Operators are available toll-free at 1-800-772-1213 on weekdays from 7 a.m. and 7 p.m., and those needing TTY services can call at 1-800-325-0778.

Medicare form on a wood table with a stethoscope on top.

Image source: Getty Images.

When to get Medicare

Most people aren't allowed to file for Medicare until three months before they turn 65. The initial enrollment period for Medicare runs from then until three months after your 65th birthday. By enrolling during this period, your coverage will take effect promptly, and you'll avoid any penalties for not enrolling in a timely manner.

Applying for Medicare before you turn 65 ensures that your coverage will be effective immediately upon turning 65. If you wait until later, then delays of up to three months can occur in activating your healthcare coverage.

For some, enrolling in Medicare immediately upon reaching age 65 isn't the right move. Specifically, those who get health coverage through their work or a spouse's work might prefer to stay with that separate coverage, delaying having to pay Medicare premiums for Part B coverage. As long as the outside coverage meets federal requirements, you'll be able to enroll later without penalty through a special enrollment period when that coverage goes away. Be sure to coordinate with the personnel department at your work or your spouse's work to avoid any miscommunication when it comes to Medicare enrollment.

Choosing traditional Medicare or Medicare Advantage

Medicare offers two different sets of programs: traditional Medicare and Medicare Advantage, also known as Medicare Part C. The difference between the two programs is that although traditional Medicare runs entirely through the federal government, Medicare Advantage involves private insurance companies that offer similar coverage that the government provides. Medicare Advantage also often incorporates features of what you'd need separate coverage to receive under traditional Medicare, including Part D prescription drug coverage as well as out-of-pocket maximums and other risk-management tools.

Picking between traditional Medicare and Medicare Advantage isn't always easy, but it can make a huge difference in your total healthcare expenses. Looking closely at both options is smart to ensure that you get the most from your Medicare coverage.

The first thing that Medicare gives you

Once you join Medicare, you'll want to take advantage of some immediate benefits. Within the first 12 months you're part of Medicare, you can get a preventive visit designed to set a health condition baseline and answer any questions you have about your health. Using this free visit is a great way to get off on the right foot.

If you're looking to join Medicare in 2018, you'll want to know everything you can about the program. This guide is a good starting point to get you thinking about your Medicare coverage and how to take full advantage of your health benefits in retirement.