As with most health care plans, Medicare plans have an annual open enrollment period. During this time, current Medicare users get a chance to evaluate their coverage and potentially make changes.

Medicare has one main open enrollment window from Oct. 15 to Dec. 7 each year. However, there’s also a Medicare Advantage open enrollment period annually from Jan. 1 to March 31.

What is Medicare open enrollment?

Open enrollment is the health care user’s chance to evaluate the plan they have, take a look at what’s on the market and update their coverage for the coming year. Open enrollment is for consumers who already have Original Medicare or Medicare Advantage.

During the main open enrollment period, from Oct. 15 to Dec. 7, any changes you make will take effect on Jan. 1. During the Medicare Advantage open enrollment period, any changes you make will take effect on the first of the month after the plan receives your request.

What you can change

There are several things you can alter during open enrollment. From Oct. 15 to Dec. 7, you can do the following things:

  • Switch from Original Medicare to a Medicare Advantage Plan.
  • Switch from a Medicare Advantage Plan back to Original Medicare.
  • Move from one Medicare Advantage Plan to a different one.
  • Join a Medicare prescription drug plan.
  • Switch from one Medicare prescription drug plan to another one
  • Drop your Medicare prescription drug coverage

From Jan. 1 to March 31, Medicare Advantage open enrollment, you can do the following things:

  • Switch from one Medicare Advantage Plan to another.
  • Quit your Medicare Advantage Plan and go back to Original Medicare, with the option to join a Medicare Prescription Drug Plan.

While it’s possible to switch from a Medicare Advantage Plan and go back to Original Medicare during both periods, it’s only possible to do the reverse (move from Original to Advantage) from Oct. 15 to Dec. 7.

Comparing Original Medicare and Medicare Advantage

If you have an Original Medicare plan — you’re enrolled in Medicare Part A and Medicare Part B — open enrollment is the time when you might consider switching to a Medicare Advantage Plan. For some people, purchasing a Medicare Advantage Plan feels simpler.

“Some people prefer the sense of a one-stop shop,” says Deborah Gordon, author of “The Health Care Consumer’s Manifesto: How to Get the Most for Your Money.” “Like, ‘I cannot deal with A, B, D, I just want a health plan.’”

Here’s what you should know:

  • Medicare Advantage Plans offer all the benefits of Part A and Part B. You won’t get less coverage with an Advantage plan.
  • Most Medicare Advantage Plans provide prescription drug coverage. If you stick with Original Medicare, you’ll have to sign up for Medicare Part D for prescription drug coverage.
  • Medicare Advantage Plans usually offer coverage for things that aren’t included under Original Medicare, such as dental, vision, hearing and wellness programs.
  • With a Medicare Advantage Plan, you must use health care providers that are in the plan’s network, and you may need a referral to see a specialist. With Original Medicare, you can use any health care provider in the United States that takes Medicare, and you usually won’t need a referral.
  • Some Medicare Advantage Plans may include lower out-of-pocket costs than Original Medicare. Original Medicare users may have to purchase supplemental coverage to help cover out-of-pocket costs.
  • Under Original Medicare, there is no limit on your out-of-pocket costs each year. With a Medicare Advantage Plan, once you spend a certain amount, the plan will cover 100% of the costs for the rest of the year.
  • While neither plan covers you if you travel outside of the U.S., you may be able to purchase a supplemental policy that would cover you in a foreign country if you have Original Medicare. Under Medicare Advantage, you can’t purchase any supplemental coverage plans.

How to compare Medicare Advantage Plans

Choosing a Medicare Advantage Plan can be a little intimidating because there are so many plans available. “The average Medicare beneficiary has something like two dozen choices,” Gordon says. “That seems great, like, ‘Oh, you have so many options,’ but it can be really overwhelming to consumers.”

There are five different types of Medicare Advantage Plans:

  • Health Maintenance Organization, or HMO, plans: This kind of plan requires you to see an in-network provider unless it’s an emergency situation. Most require you to get a referral to see a specialist.
  • Preferred Provider Organization, or PPO, plans: This kind of plan allows you to see both in-network and out-of-network health care providers, although it typically is more expensive to go out of network.
  • Private Fee-for-Service, or PFFS, plans: This kind of plan allows you to see any Medicare-approved health care provider as long as they accept the plan’s payment terms and agree to see you, and you may also have access to a network of providers. You can see doctors that don’t accept the plan’s payment terms, but you might pay more.
  • Special Needs Plans, or SNPs: This kind of plan provides benefits to people with certain diseases, such as cancer, or health care needs, such as living in a nursing home. It also provides benefits to people with a limited income.
  • Medical Savings Account, or MSA, plans: These combine a high-deductible insurance plan with a medical savings account that can be used for health care costs.

Choosing between Medicare Advantage Plans will require you to understand your health care needs and think about what each type of plan offers. If you have a chronic health condition and you love your doctors, you’ll want health coverage that they accept. If you take prescription drugs, some plans may result in lower out-of-pocket costs than others.

Here are some questions to ask:

  • Do you have to get a referral? Some plans require you to get a referral from your primary care physician in order to see a specialist. If that’s not your preference, you’ll want to choose a plan with more freedom.
  • What benefits do they include? Do you need vision and dental coverage? Look for a plan that offers the benefits you want.
  • How much will your drugs cost? If you’re taking regular prescription drugs, compare costs within each plan to make sure you understand what you’ll be paying.
  • Are your doctors covered? If you like your providers, find out whether they’re included in the networks of the plans you’re considering.
  • What’s their rating? Each Medicare Advantage Plan comes with a star rating that ranges from one star to five stars. “I talked to a consumer in Massachusetts who essentially [won’t consider] any plan below a four-star plan,” Gordon says.

For additional help, try the Medicare Plan Finder on Medicare’s website.

How to switch Medicare Advantage Plans

If you’re already in a Medicare Advantage Plan, you can switch to a different Medicare Advantage Plan during either open enrollment period: Oct. 15 to Dec. 7, or Jan. 1 to March 31. After you join a new plan, you’ll be automatically unenrolled from your old plan once your new one starts.