Medicare can be complicated, but several great resources can help you get answers to your Medicare questions — whether you want to know more about costs, coverage, eligibility, enrollment or how to choose supplemental policies.

1. Centers for Medicare & Medicaid Services (CMS)

This federal agency, which is part of the U.S. Department of Health and Human Services, runs the Medicare program. Its website offers information about how Medicare works, what it covers, when to enroll, Medicare costs, claims questions, how to appeal a coverage or payment decision and how to buy private insurance policies that can fill in coverage gaps.

The Medicare Plan Finder is the best way to find out about the costs and coverage for the Part D prescription drug plans and the private Medicare Advantage plans available in your area, whether you’re choosing a plan when you’re first eligible or during open enrollment each year.

If you have questions about Medicare rules, coverage and claims, call Medicare’s help line at 800-633-4227 or use the Live Chat function, which is generally available 24/7 except for some federal holidays. Information is available in about two dozen languages, including English and Spanish.

The Medicare & You handbook, updated annually, explains what Medicare covers, how it works, when you need to sign up and any changes to the rules.

2. Social Security Administration

Even though CMS runs the Medicare program, the Social Security Administration handles Medicare enrollment. You can enroll in Medicare on the SSA website during your initial enrollment period or a special enrollment period, or you can visit an SSA office to sign up during those and other times.

The agency can also help with questions about Medicare enrollment and eligibility; applying for the Part D prescription drug Extra Help program, which provides financial assistance for Medicare beneficiaries with low income and assets; and contesting Medicare’s high-income premium surcharges.

The national toll-free phone number is 800-772-1213. You can also visit your local Social Security office.

3. State Health Insurance Assistance Programs

State Health Insurance Assistance Programs (SHIPs) are available in every state plus the District of Columbia, Guam, Puerto Rico and the U.S. Virgin Islands. These programs are a public service that provide personal help from trained counselors on all Medicare issues.

More than 12,500 SHIP counselors provide free one-on-one counseling, seminars and outreach programs, especially during the Oct. 15 to Dec. 7 annual open enrollment period. They can answer questions over the phone, in person or online

Search online for a SHIP in your area or call 877-839-2675.

4. Medicare Rights Center

The Medicare Rights Center has been helping people navigate Medicare for more than 30 years. Counselors can answer questions about Medicare rules, deadlines, enrollment, choices and claims. They are available through the organization’s national helpline at 800-333-4114.

This nonprofit also runs the Medicare Interactive website, which explains in detail how Medicare works and answers frequently asked questions about the program.

5. AARP Medicare Resource Center

AARP’s Medicare Resource Center has stories that can give you an overview about the way Medicare works, news on the latest changes and developments, answers to questions that go more in depth and a link to the Medicare Enrollment Guide, which can introduce you and your friends to the health care benefit that covers nearly 1 in 5 Americans.

Among the other resources you’ll find:

  • Step-by-step tutorials on how to use Medicare’s Plan Finder, to learn about Medicare Advantage, Medigap and Part D prescription drug plans in your area
  • On-demand webinars that teach you about key times and potential problems as you approach Medicare age and deal with this program for the rest of your life
  • Videos that give a quick overview on issues, demystifying the complex topic of Medicare. They accompany the relevant articles.

Have additional Medicare questions? AARP can help. Call 877-634-8213 toll free, from 8 a.m. to 8 p.m. eastern time on weekdays, to speak to an AARP Help Center representative. If you prefer to look online, the chat feature in our digital AARP Help Center can help you with questions you type in.

Keep in mind

Even though Medicare is a federal program, you can find helpful information from your state insurance department, especially about supplemental Medigap policies, which help cover Medicare’s deductibles and copays. Most state insurance department websites have lists of prices and contact information for insurers selling Medigap policies in the state, as well as state-specific Medigap rules.