Medicare Part B enrollment windows and important date
You can sign up for Medicare Part B during three main periods: your Initial Enrollment Period, your General Enrollment Period, or a Special Enrollment Period if you may have access to. The timing depends on when you turn 65 and whether you already have coverage through an employer or union.
Your Initial Enrollment Period is a seven-calendar-month window centered on the month you turn 65. It starts three months before the month you turn 65, includes that month, and ends three months after. For example, if you turn 65 in June, your Initial Enrollment Period runs from March through September. You can enroll any time during this window, and coverage can start as early as the first day of the month you turn 65.
If you miss your Initial Enrollment Period, you can sign up during the General Enrollment Period, which runs January 1 through March 31 each year. Coverage begins July 1 of that year. However, you will likely pay a late enrollment penalty — an extra amount added to your Part B premium for as long as you have Medicare. The penalty is 10 percent of the standard Part B premium for each full 12-month period you were may be able to access but did not enroll.
Key Takeaways
- Your Initial Enrollment Period is seven months long, centered on the month you turn 65, and is the only time you can avoid a late enrollment penalty.
- If you have employer or union coverage when you turn 65, you may be able to delay Part B enrollment without penalty, but you must enroll within eight months of losing that coverage.
- The General Enrollment Period (January 1 through March 31) is open to anyone, but enrollment during this period triggers a permanent late enrollment penalty.
- Special Enrollment Periods exist for specific situations like losing employer coverage or moving to a new state, and they let you enroll without penalty outside the normal windows.
- You enroll through Social Security, Medicare.gov, or your local Social Security office — not through your doctor or insurance company.
Delaying Part B if you have employer coverage
If you or your spouse are still working and covered by an employer or union health plan when you turn 65, you do not have to enroll in Part B right away. You can delay enrollment without facing a late enrollment penalty, as long as you enroll within eight months after your employment or coverage ends, whichever comes first.
This rule applies only if the employer has 20 or more employees. If your employer has fewer than 20 employees, Medicare becomes your primary payer when you turn 65, and you should enroll in Part B during your Initial Enrollment Period to avoid penalties.
When you do decide to enroll after leaving your job, contact Social Security or visit Medicare.gov to start the process. You will need to show proof that you had employer coverage — your employer or benefits administrator can provide a letter stating the coverage dates and the number of employees.
Special Enrollment Periods for life changes
A Special Enrollment Period lets you enroll in Part B outside the normal windows without paying a late enrollment penalty. These periods are triggered by specific events, and you typically have two months from the event to enroll.
Common may have access to events include losing employer or union coverage, moving to a new state, losing Medicaid, or having a change in your immigration status. If you are a federal employee, you may also have a Special Enrollment Period when your federal employee health benefits plan ends.
To use a Special Enrollment Period, you must contact Social Security or Medicare and provide documentation of the event — such as a letter from your employer stating when coverage ended, or proof of your move. Social Security will verify your situation and tell you whether you may have access to and when your coverage can start.
How to enroll during your enrollment period
You have three ways to enroll in Part B: online through Medicare.gov, by phone with Social Security, or in person at your local Social Security office.
Online enrollment is the fastest route. Visit Medicare.gov, sign in with your Medicare account (or create one), and follow the prompts to enroll in Part B. You will need your Social Security number and basic personal information. The system will confirm your enrollment window and show you when coverage starts.
Phone enrollment is available by calling Social Security at 1-800-772-1213 (TTY 1-800-325-0778). Have your Social Security number and date of birth ready. Social Security staff can answer questions about your specific situation and enroll you on the spot. Wait times are typically shorter early in the morning or on weekdays.
In-person enrollment at your local Social Security office is an option if you prefer to speak with someone face-to-face. Find your office at ssa.gov/locator. Bring your Social Security card, proof of citizenship or legal residency, and a photo ID. No appointment is required, but you may wait longer during peak hours.
What happens if you miss your enrollment window
If you miss your Initial Enrollment Period and do not have a may have access to Special Enrollment Period, you can enroll during the General Enrollment Period (January 1 through March 31). However, you will owe a late enrollment penalty for as long as you have Medicare.
The penalty is calculated as 10 percent of the standard Part B premium for each full 12-month period you were may be able to access but did not enroll. If you were may be able to access for three years before enrolling, your penalty would be 30 percent of the standard premium. This penalty does not go away even if you switch plans or move to a different state.
There is one exception: if you were covered by Medicaid when you turned 65, you may not owe a penalty if you enroll within a certain timeframe. Contact Social Security to find out whether this applies to your situation.
Part B coverage start dates by enrollment timing
| When You Enroll | Coverage Start Date |
|---|---|
| During Initial Enrollment Period (3 months before through 3 months after month you turn 65) | As early as the first day of the month you turn 65, depending on when in the period you enroll |
| During General Enrollment Period (January 1 – March 31) | July 1 of that year |
| During a Special Enrollment Period | Varies by situation; Social Security will tell you the date |
Frequently Asked Questions
Can I enroll in Part B before I turn 65?
Yes. Your Initial Enrollment Period starts three months before the month you turn 65, so you can enroll as early as three months in advance. Many people enroll during this early window to may support coverage starts on their 65th birthday without any gaps.
What if I turn 65 but am still working and do not want Part B yet?
If your employer has 20 or more employees and you are covered by their health plan, you can delay Part B without penalty. You have eight months after you leave your job or lose coverage to enroll. If your employer has fewer than 20 employees, you should enroll during your Initial Enrollment Period to avoid a penalty.
Do I have to enroll in Part A at the same time as Part B?
No. Part A and Part B are separate. However, most people are automatically enrolled in Part A when they turn 65 if they are receiving Social Security benefits. You can enroll in Part B independently during any of your enrollment periods, regardless of your Part A status.
What if I moved to a different state after turning 65?
Moving to a new state qualifies you for a Special Enrollment Period. You have two months from the date you move to enroll in Part B without penalty. Contact Social Security with proof of your move, such as a utility bill or lease showing your new address and move date.
How much does Part B cost?
The standard Part B premium changes each year. For 2024, the standard premium is $164.90 per month, but your actual premium may be higher based on your income. Higher-income beneficiaries pay an Income-Related Monthly Adjustment Amount (IRMAA) on top of the standard premium. Social Security will tell you your specific premium amount when you enroll.