The annual Medicare open enrollment period runs from October 15 to December 7 each year, KFF reports. During the nearly 8-week window, people with Medicare can review the plans offered in their area and make changes, which take effect on January 1 of the following year.

What you can change depends on how you get Medicare, according to KFF. People in traditional Medicare can enroll in a Part D prescription drug plan or switch between Part D plans, though those who skipped Part D when they first enrolled may face a late enrollment penalty if they did not have comparable drug coverage before. People in a Medicare Advantage plan can choose a different Medicare Advantage plan or move to traditional Medicare.

KFF encourages beneficiaries to review their current coverage and compare other options available where they live. Even so, it reports that nearly two-thirds, 65%, of Medicare beneficiaries did not compare their options during the open enrollment period for 2025 coverage. One caution from KFF: people with retiree health coverage offered only through a Medicare Advantage plan might lose those benefits if they switch to traditional Medicare.

Medicare Advantage enrollees get another chance to switch plans or move to traditional Medicare from January 1 through March 31, KFF notes, and special enrollment periods apply in certain circumstances. To compare plans, KFF points to the Medicare Plan Compare tool on Medicare.gov, the 1-800-MEDICARE line (1-800-633-4227) and local State Health Insurance Assistance Programs.