Medicare is a federal health insurance program that covers the cost of hospital care (Part A) and doctor visits (Part B) for adults age 65 and older, people with disabilities, and people with certain medical conditions. Medicare Parts A and B are referred to as original Medicare.

Other parts of Medicare include Part D (prescription drug coverage) and Part C (Medicare Advantage), which is an alternative way to get your original Medicare and often your Part D coverage in one plan. Medicare Part D and Part C are offered through private health insurance companies. To enroll in a these plans, you must already be enrolled in original Medicare. Eligible older adults can sign up for Medicare health and drug plans during the Open Enrollment Period, which runs from Oct. 15-Dec. 7 each year.

Can you use Medicare anywhere in the U.S.?

One thing many older adults wonder is whether their Medicare benefits are portable. If you travel often within the U.S., you should know original Medicare covers hospital care and doctor visits in all 50 U.S. states as well as Washington, D.C., Puerto Rico; the U.S. Virgin Islands; Guam; American Samoa; and the Northern Mariana Islands. There are no network restrictions; you can see any provider that accepts Medicare.

Certain Medicare Advantage plans also provide state-to-state coverage, including a national pharmacy network that allows you to pick up your prescription medications at locations across the country. Other Medicare Advantage plans may not cover care outside of their defined service area—or they may impose higher cost-sharing or prior-authorization rules for out-of-network care. All of these plans are required to cover emergency and urgent care anywhere in the U.S. without additional restrictions or out-of-pocket costs.

Will you be spending a large amount of time at a second home, with family, or at a long-term vacation rental? If you have an Medicare Advantage plan, be sure you understand its rules before heading out on an extended stay. Consider this:

Does Medicare cover international travel?

Original Medicare usually does not cover health care you receive while traveling outside of the United States and its territories, except in very specific emergency situations. In these scenarios below, Medicare pays only for its share of Part A and Part B covered services.:

Medicare Part D drug plans won't cover prescription medications you buy outside the United States. If you have to buy medication from an international pharmacy, you should expect to pay 100% of the cost out of pocket.

Medicare Advantage plans must cover, at a minimum, everything original Medicare covers. As a result, your plan will usually cover international travel in the instances outlined above. Some Medicare Advantage plans also offer additional benefits for emergency care and urgent care services during foreign travel. Keep in mind that this coverage is generally meant for unexpected situations, not for routine health care visits while you are abroad.

You may get disenrolled from your Medicare Advantage plan and returned to original Medicare if you travel outside the U.S. for more than six months. Medicare Advantage coverage and rules vary from plan to plan—so be sure to check with your plan provider before traveling outside the country. They can tell you whether your plan offers emergency travel benefits and how claims or reimbursement are handled.

What about Medigap? Are Medigap plans accepted everywhere?

Sold by private companies, Medigap (also known as Medicare Supplement) is a supplemental insurance policy that can be used alongside Original Medicare to fill any gaps in coverage. If you have a Medigap policy, it will cover a portion or all of certain remaining costs after original Medicare pays its share. These costs can include deductibles, coinsurance, and copayments. You cannot use a Medigap policy with a Medicare Advantage plan (only original Medicare).

Some Medigap policies pay for medical services that don’t fall under original Medicare, such as doctor or hospital visits that take place when you’re traveling abroad. Medigap plans C through G, M, and N cover 80% of foreign emergency care costs. Each policy has its own coverage rules.

The bottom line: Are you covered by Medicare if you're traveling?

If you have original Medicare or a Medicare Advantage plan, you'll be covered for emergency care while traveling anywhere in the U.S. Keep in mind that if you have a Medicare Advantage plan, you may not be covered for routine health care beyond your plan's service area.

Outside the U.S., Medicare coverage is limited.

Certain Medicare Advantage plans and Medigap policies may offer some additional coverage for foreign travel. Before your trip, check with your plan to see exactly what it does and does not cover.

Overall, if you're headed to a foreign destination for your next vacation, your Medicare coverage may be very limited, even in an emergency. In most cases, you will not be reimbursed for international medical bills—so expect to pay 100% of these costs out of pocket.

The good news is you can consider buying travel health insurance to expand your foreign health care coverage, which will allow you to roam the globe with more peace of mind. Talk to a trusted insurance or travel agent for more details on coverage and cost.