To switch to Medicare, you can generally do so during the Medicare Initial Enrollment Period (IEP), which begins three months before the month you turn 65, includes the month you turn 65, and ends three months after the month you turn 65. This is the most common time to enroll in Medicare. Additionally, there are other enrollment periods such as the General Enrollment Period and Special Enrollment Periods for specific circumstances. It's important to be aware of these enrollment periods to ensure you can transition to Medicare at the right time. If you have specific questions about your eligibility or enrollment periods, it's advisable to contact the Social Security Administration or visit the official Medicare website for personalized guidance.