Medicare Open Enrollment is from October 15th - December 7th every year, with any changes to your plan that you select becoming effective January 1st 2018.
To compare plans, see what Medicare plans are available in your area, and to enroll in a new plan visit Medicare.gov or call 800-MEDICARE (800-633-4227). Another option for information and enrolling is to call the plan of your choice or visit its website. AARP encourages anyone who is on a Medicare plan or eligible for enrolling to review their options during the enrollment period. Many plans change and so do your health needs over the year so take this time to ensure that the plan you are using is the best fit for you.