Medicare Part B covers two kinds of health services: medically necessary care and preventive care.You need to think twice about saying no to Medicare Part B coverage, even though it costs a monthly premium to use it. (If that amount would be a hardship, you may be able to have the premiums paid by your state.) It’s an important decision you need to make during the enrollment process — especially if you’re signed up automatically — and you should be very clear on how to deal with it given your situation.

You may think that disenrolling means the same as opting out. And that may be so in general. But in a specific situation where you’re already enrolled in Part B, but then — weeks, months, or years later — you or your spouse starts a job with health benefits. If that happens, do you really need to keep on paying those Part B premiums?

If you’re new to Medicare (or soon will be), here's information on three crucial Medicare topics: a useful list of dos and don’ts to keep in mind before you embark on the program; a quick run-through of the best times to enroll, depending on your specific circumstances; and a mini-directory of organizations that can help you with Medicare issues.

Although Medicare covers a multitude of medical services, it also has some yawning gaps. Some may surprise you, so the following sections address the broad areas that Medicare doesn’t normally cover, together with some tips for alternative ways of filling in the gaps. Being aware of them from the start is better than being disappointed if Medicare denies coverage after the fact.

Part D, Medicare's program for covering prescription drugs, is a complicated benefit that resembles no other type of drug coverage ever devised. That's why understanding how it works before plunging in is really important. Following is information on the peculiarities of Part D coverage — how it can fluctuate during the year, how different plans have their own lists of drugs they cover, and which drugs are excluded from Part D and which must be covered.

Part A and Part B form the core of Medicare. They provide the coverage that you have if you enroll in the traditional or original Medicare program that has been around since 1966, although many more services have been added since then.Parts A and B are also the basis of your coverage if you’re in a Medicare Advantage health plan, because all those plans must by law cover the same services as the traditional program, although the plans can provide extra benefits if they want to.

When the prospect of becoming a Medicare beneficiary looms on the horizon, you suddenly become aware — if you’re like most people — of how little you know about the program. And even if you think you know, can you be sure that the information you have is accurate? © Jerome.Romme / Shutterstock.comBased on the questions most frequently asked, it seems a lot of perceptions about Medicare are way off base; quite often, they’re gleaned from the Internet or even mass e-mails that are deliberately designed to spread misleading information and scare seniors.