Many Americans don't realize that if they want Medicare coverage, they don't have to sign up for the U.S. government-provided original Medicare coverage. Private insurance companies such as Blue Cross Blue Shield and UnitedHealth Group now offer Medicare Advantage plans. Should you get a Medicare Advantage plan? You may well want to. Lots of people have done so, and they can be compelling.

Medicare Advantage plans, in a nutshell

Medicare Advantage plans debuted in 1995. They're administered by private insurers but are regulated by the U.S. government. Each must offer at least as much coverage as what is now called "original Medicare" (i.e., the benefits you'll find in Part A and Part B that respectively cover hospital and medical services). In order to attract customers, though, many go beyond original Medicare, offering broader coverage, such as vision care, dental care, and/or prescription drug coverage.

Medicare Advantage plans are offered mainly in the following formats: Health Maintenance Organizations (HMOs), Preferred Provider Organizations (PPOs), Private Fee-For-Service (PFFS) plans, and Special Needs Plans (SNPs).

Should you get a Medicare Advantage plan?

Medicare Advantage plans offer many upsides, but there are some downsides to consider, as well. For starters, while original Medicare will often have you footing 20% of many bills, a Medicare Advantage plan  might charge you a low copay per doctor visit or service. Medicare Advantage plans also have out-of-pocket limits, beyond which the plan will pick up all your healthcare costs for the year. The average out-of-pocket cap was recently $5,223, but many plans feature limits below $3,000 and the limit in 2016 was $6,700. That can be a huge plus to many people, because original Medicare has no out-of-pocket spending limit. With a Medicare Advantage plan, you will have peace of mind from knowing your costs are capped.

Medicare Advantage plans with the HMO format will typically mandate that you have a primary care doctor who must give you any referrals to specialists, instead of your simply finding and seeing a specialist on your own. HMOs will usually only cover services provided within their own networks. In exchange for these restrictions, you'll often pay less. A restricted network can be a problem if you travel a lot, but on the other hand, while original Medicare plans don't cover healthcare provided outside the U.S., some Medicare Advantage plans do.

Medicare Advantage plans with the PPO format will typically let you patronize any doctor or hospital, but will offer favorable terms if you choose those that are in-network. These plans can cost more, but offer more freedom and that might matter a lot to you if it's very important to you to be able to continue seeing a certain doctor or doctors. Keep up with your plans, too, as sometimes the doctor networks change. United Healthcare, for example, has cut  thousands of doctors from its Medicare Advantage networks in recent years.

Medicare Advantage plans also have these advantages: They offer relatively comprehensive coverage in a single policy, so that you don't have to fill gaps with additional coverage. Many plans charge the enrollee nothing in premiums. The Medicare program pays the insurance company offering it a set sum per enrollee and if the insurer thinks it can make a profit without charging its customers much, it can offer compelling pricing.

What to do

If you think you might be interested in a Medicare Advantage plan, see which ones are offered in your area. You can go to the Medicare website and click on the "Find Health and Drug Plans" button to start the process. Learn about plans available to you and see whether any make sense for you. Review your options carefully, since each insurance company's Medicare Advantage plan(s) will likely vary from those of other insurers in terms of their rules and what they charge and provide. Each kind won't be available in each state, either. Check out which doctors and hospitals are in-network for any plan you're considering.

Know, too, that choosing between original Medicare and a Medicare Advantage plan isn't a permanent decision. At least once a year, you will be able to switch between them during the open enrollment period.

Don't dismiss Medicare Advantage plans without seeing just what kinds of plans are available to you and what they offer.