According to the Medicare Website – If you sign up for Medicare Part A (Hospital Insurance) and/or Medicare Part B (Medical Insurance) during the first 3 months of your Initial Enrollment Period, your coverage starts the first day of your birthday month, unless your birthday is on the first day of the month. http://www.medicare.gov/sign-up-change-plans/get-parts-a-and-b/when-coverage-starts/when-coverage-starts.html