By David Sayen for U.S. Centers for Medicare & Medicaid Services

Medicare open enrollment period begins Oct. 15 and runs through Dec. 7, 2015.

If you have Original Medicare, meaning that you can choose any doctor or hospital that accepts Medicare, you don’t need to think about open enrollment.

But if you have a Medicare Advantage (Part C) health plan, or a Medicare (Part D) prescription drug plan, you may want to see if there’s a new plan on the market that would be a better match for you, at a lower price.

If you’re enrolled in a plan already and you’re happy with it, you don’t need to do anything. But Medicare health and drug plans — which are run by private insurers under contract to Medicare — can change from year to year. A plan can raise its monthly premium or drop a medicine that you need.

Make sure your plan still is a good fit for you in terms of cost, coverage, and quality. If it isn’t, look for another plan.

During open enrollment, you can sign up for a Medicare Advantage health plan or Part D prescription drug plan, or switch from one plan to another. Your new coverage will take effect Jan. 1, 2016.

There are several ways to shop for a new plan.

One is the “Medicare & You” handbook, which is mailed each fall to every Medicare household in the country. This booklet lists all the Medicare Advantage and Part D drug plans that are available where you live, along with basic information such as premiums, deductibles, and contact information.

There’s also the Medicare Plan Finder at the website. Look for a green button that says, “Find health & drug plans.” By clicking on that and plugging in your zip code, you’ll be able to see all of the Medicare Advantage and Part D plans available in your area. You can compare them based on benefits, premiums, co-pays, and estimated out-of-pocket costs. Contact information for the plans is listed.

If you don’t have access to a computer, call 1-800-MEDICARE (1-800-633-4227). Customer service representatives can help with questions about Medicare health and drug plans.

Another very helpful resource is California’s Health Insurance Counseling and Advocacy Program, or HICAP. California HICAP is an independent, nonprofit organization that provides free, personalized counseling to people with Medicare. You can make an appointment to speak with a HICAP counselor either in-person or over the phone. To contact HICAP, call 800-434-0222.

If you’re enrolled in a Medicare Advantage plan as of Jan. 1, 2016, but you’re not satisfied with it, you have a 45-day window to disenroll. Between Jan. 1 and Feb. 14, 2016, you can drop your plan and return to Original Medicare. You can also sign up for a Part D drug plan during that time.