When to Sign Up for Medicare: Enrollment Periods Explained

Sign up during your Initial Enrollment Period, which “lasts for 7 months, starting 3 months before you turn 65, and ending 3 months after the month you turn 65,” says Medicare.gov. Miss it and you wait for the General Enrollment Period, January 1 to March 31, and may pay a late penalty.

The short answer

• Initial Enrollment Period: 7 months. It covers the 3 months before the month you turn 65, your birthday month, and the 3 months after.
• General Enrollment Period: January 1 to March 31 each year. Coverage starts the month after you sign up.
• Special Enrollment Period: often 8 months after you or your spouse stop working or job-based coverage ends.
• Penalty: it goes up the longer you wait, and you might pay it for as long as you have Part B.

When should you apply for Medicare?

Apply early in your Initial Enrollment Period. When you apply decides when coverage starts:

• Premium-free Part A starts the month you turn 65. If your birthday is on the 1st, it starts the month before.
• Part B, and Part A with a premium, start the month you turn 65 if you sign up before that month.
• If you sign up during your birthday month or the three months after, coverage starts the following month.

Example: you turn 65 in July. Sign up in April, May or June and Part B starts in July. Sign up in July or any of the next three months and it starts one month later, leaving a gap.

What if you miss the Initial Enrollment Period?

Use the General Enrollment Period, January 1 to March 31 each year. Coverage starts the month after you sign up. Late enrollment penalties may apply, and Medicare.gov lists the Part B penalty amount on a separate page, so check it before you delay.

What is the Special Enrollment Period?

The most common is an 8-month period that starts when you or your spouse stop working. It lets you sign up for Part B without waiting for January. The same 8 months apply if job-based coverage ends first.

When is Open Enrollment?

A search summary gave October 15 to December 7, with changes starting January 1, 2027 for the 2027 plan year, and a Medicare Advantage Open Enrollment from January 1 to March 31 for people already in an MA plan. Confirm these dates on Medicare.gov before you rely on them.

Who can wait, and what should you do next?

Still working with job-based coverage? You may wait, because the 8-month Special Enrollment Period protects you. Without that coverage, do not wait.

1. Mark the first day of your Initial Enrollment Period: three months before your birthday month.
2. Sign up in that window, ideally before your birthday month so Part B starts on time.
3. If you keep working, note the date you or your spouse stop and count 8 months from it.
4. Check the Part B penalty amount on Medicare.gov before any delay.

Questions and answers about signing up for Medicare

When does coverage start if I sign up early?

Part B starts the month you turn 65 if you sign up before that month.

How long is the Initial Enrollment Period?

7 months: 3 before the month you turn 65, the birthday month, and 3 after.

What if I sign up in my birthday month?

Coverage starts the following month.

When does the General Enrollment Period run?

January 1 to March 31 each year, with coverage starting the month after you sign up.

Can I delay Part B while I work?

Yes. Your 8-month Special Enrollment Period to sign up for Part B starts when you stop working.

Will I pay a penalty for signing up late?

Possibly. It grows the longer you wait and can last as long as you have Part B.

Sources

• Medicare.gov: when does coverage start?
• Medicare.gov: when can I sign up?

This guide is general information, not insurance advice.

Facts last checked on 20 October 2026.