When does Medicare coverage start?

When does Medicare start if I sign up when I turn 65?

It depends on the month you sign up during your Initial Enrollment Period, the 7 months that start 3 months before the month you turn 65 and end 3 months after the month you turn 65. Medicare.gov says coverage always starts on the first of the month:

• Premium-free Part A: starts the month you turn 65.
• Part B (and Part A you pay a premium for), signed up before the month you turn 65: starts the month you turn 65.
• Signed up the month you turn 65, or during the 3 months after: starts the next month.
• Birthday on the 1st of the month: your 7-month period starts 4 months before you turn 65 and ends 2 months after the month you turn 65, and coverage generally starts the first day of the month before you turn 65. With a June 1 birthday, the period runs February to August, and signing up in February, March or April means coverage starts May 1.
• Already getting Social Security or Railroad Retirement Board benefits: you get Part A and Part B automatically starting the first day of the month you turn 65 (the prior month if your birthday is on the 1st). If you live in Puerto Rico, you don't get Part B automatically and must sign up for it.

When does Part A start if I sign up after 65?

If you qualify for premium-free Part A, you can sign up any time after you turn 65. Your Part A coverage starts 6 months back from when you sign up or apply for benefits from Social Security (or the Railroad Retirement Board), but it can't start earlier than the month you turned 65.

Because Part A can start up to 6 months back, Medicare.gov suggests you and your employer consider stopping Health Savings Account (HSA) contributions at least 6 months before you apply for Medicare, which may help you avoid a tax penalty. See Can I contribute to an HSA once I have Medicare?.

When does Medicare start if I sign up after my Initial Enrollment Period?

After your Initial Enrollment Period ends, you can sign up for Part B (and Part A you pay a premium for) only during another enrollment period. In the General Enrollment Period, January 1 to March 31 each year, your coverage starts the month after you sign up, and you might pay a monthly late enrollment penalty if you don't qualify for a Special Enrollment Period. Special Enrollment Periods set their own start dates:

• Health insurance through your job or your spouse's job (or a family member's job if you have a disability): coverage generally starts the first month after you sign up. If you sign up while you (or your spouse) are still working, or within the first full month after employer coverage ends, you can ask to delay your Part B start date up to 3 months.
• Lost Medicaid coverage: coverage starts the month after you sign up, or the date your Medicaid coverage ends, whichever you choose.
• Released from incarceration: coverage starts the month after you sign up, or you can choose coverage back to your release date, up to 6 months in the past.
• A natural disaster or emergency, inaccurate or misleading information from your health plan or employer, or other exceptional conditions that made you miss a chance to sign up: coverage starts the month after you sign up.
• TRICARE: coverage starts the month after you sign up, or you may choose for it to begin after the end of your Initial Enrollment Period.

When does Medicare start if I'm under 65?

If you're under 65 and have a disability, you get Part A and Part B automatically after getting 24 months of disability benefits from Social Security or certain disability benefits from the Railroad Retirement Board, and your Medicare card arrives 3 months before your 25th month of benefits. If you have ALS (Lou Gehrig's disease), you get Part A and Part B automatically the month your Social Security disability benefits begin.

With End-Stage Renal Disease (ESRD), Medicare coverage usually starts on the first day of the fourth month of dialysis treatments, even if you haven't signed up yet. It can start as early as the first month of regular dialysis if you take part in a home dialysis training program at a Medicare-certified training facility during the first 3 months of regular dialysis, your doctor expects you to finish training and do your own dialysis at home, and you maintain a regular course of dialysis throughout the waiting period that would otherwise apply. For a kidney transplant, coverage can begin the month you're admitted to a Medicare-certified hospital if the transplant takes place that month or within the next 2 months. If you don't sign up right away, ESRD coverage could start up to 12 months before the month you apply. See How does Medicare work if I have kidney failure (ESRD)?.

When does a Medicare Advantage or Part D plan start?

When you first join in your Initial Enrollment Period, if you ask to join a Medicare Advantage Plan or Medicare drug plan before your Part A and/or Part B starts, your plan coverage starts the same day your Part A and/or Part B starts. If you ask to join after your Part A and/or Part B starts, plan coverage starts the first of the month after the plan gets your request.

Changes you make during Open Enrollment, October 15 to December 7, start January 1 of the next year, as long as the plan gets your request by December 7. Changes during the Medicare Advantage Open Enrollment Period, January 1 to March 31, start the first of the month after the plan gets your request. See What is the Medicare Advantage Open Enrollment Period?.