Each of the three Medicare enrollment periods — initial, special and general — serves a different purpose, and you may qualify for more than one at different times in your life.
If you’re already receiving Social Security benefits at least four months before you turn 65, you won’t need to take advantage of any of those enrollment periods. You’ll be signed up automatically for Medicare, effective at the beginning of your birthday month or the start of the previous month if your birthday is on the first. You should receive your Medicare card in the mail three months before your coverage starts.
If you don’t get Social Security yet, you need to sign up for Medicare. You can enroll only at certain times, so if you miss key deadlines, you could end up with late enrollment penalties and coverage gaps.
What is the Medicare initial enrollment period?
Unless you qualify for Medicare early because of a disability, the first time you can enroll is during the seven-month initial enrollment period that starts three months before the month you turn 65 and ends three full months after your birthday month. Those with first of the month birthdays get a head start on initial enrollment four months beforehand, and their seven-month window ends two months after their birth month.
If you sign up before your birthday month, your coverage takes effect the first of the month you turn 65 or the beginning of the previous month if your birthday is on the first. If you enroll during your birthday month or three months afterward, coverage begins the first day of the following month.
If you qualify for premium-free Part A, which covers hospitalization, you can get coverage during or after your initial enrollment period without penalty. Your coverage is retroactive for up to six months but no earlier than the month you turned 65.
If you don’t sign up for Part B during your IEP, you may have to wait until the general enrollment period Jan. 1 to March 31 each year.
You may face a late enrollment penalty unless you qualify for a special enrollment period. The penalty adds 10 percent to the standard Part B premium for each 12 months you could have had Part B but didn’t and lasts for as long as you have Part B.
You may also be required to pay a Part A late enrollment penalty if you don’t qualify for premium-free Part A.
Special rules for Puerto Rico: Residents of the largest and most populous U.S. territory are enrolled automatically in Part A if they’re already receiving Social Security but not Part B. Unless you or your spouse is still working and you have health insurance from that employer, you’ll need to sign up for Part B yourself during your initial enrollment period.