Any new coverage selected during this time takes effect on January 1, 2025. If you're looking to make a change, you will need to contact the insurance company offering the plan directly. If you have questions or need help making enrollment changes, you can call 1-800-MEDICARE (1-800-633-4227).

Most Americans will enroll in a Medicare or a Medicare Advantage plan when they turn 65, and some will pay a significant penalty for late enrollment. But if you're 65 or older and still working with employer-based health insurance, you may not be required to enroll.

As Medicare's open enrollment season gets underway on Tuesday, analysts are urging seniors to keep an eye on their prescription drug policies.