Dear Mira,

Good question! That depends on a few things. If you’re already receiving retirement benefits from the Social Security Administration or Railroad Retirement Board, you should automatically be enrolled in Medicare Parts A and B. Otherwise, you will need to actively enroll by contacting the Social Security Administration. There are three times when you can enroll in Parts A and B for the first time:

Your Initial Enrollment Period (IEP): The three months before, the month of, and the three months after your 65th birthday are your Initial Enrollment Period. Because your birthday is in July, your IEP started April 1, and will end at the end of October. . If you enroll in the first 3 months of your IEP, your coverage starts the first month of your birth month, if you enroll in later months, your coverage starts the first day of the next month. If you want your coverage to begin as soon as possible—July 1—you should enroll before the end of this month.

A Special Enrollment Period (SEP): If you decide not to enroll during your Initial Enrollment Period, you may be able to enroll later during an SEP, which is based on specific circumstances. One SEP allows people who are covered by health insurance as a result of their or their spouse’s current work to enroll after their IEP has ended. To use that SEP, a person must be covered by employer-based insurance (or Part B) when they first became eligible for Medicare, and may not have a gap in employer insurance or Part B of more than 8 months. If you are currently covered by employer-based insurance, you may wish to delay enrolling in Medicare, and you will be able to enroll later as long as you qualify for the SEP. Whether this is a good idea for you will also depend on coverage and cost of your employer insurance, including whether that insurance is required to pay claims for people who are eligible for but not enrolled in Medicare.

The General Enrollment Period (GEP): If you do not enroll during your IEP and do not have an SEP, you can enroll during the annual GEP, which runs from January 1 to March 31. Many people who enroll during the GEP experience coverage gaps as they wait for the January 1 start of the enrollment period, and may face late enrollment penalties depending on the length of time between their IEP and enrollment during the GEP.

Medicare prescription drug coverage, Part D, has separate enrollment rules. The Part D Initial Enrollment Period is usually the same as your Medicare IEP. However, if you delay enrollment in both Part A and Part B (or if you live outside of the service area of any plan and are therefore not eligible to enroll in a Part D plan), your Part D IEP will be the 7 months surrounding your eligibility–triggered by enrollment in Part A or Part B or your move into the service area of a plan. If you have “creditable” drug coverage, you can decline Part D without a later penalty, but you may have to wait until the Annual Election Period (also known as “Fall Open Enrollment”) from October 15 through December 7, unless one of the Part D-related SEPs is applicable.

Best of luck!

-Marci