What Is the Initial Enrollment Period?
The Initial Enrollment Period (IEP) is your first opportunity to sign up for Medicare. It is a 7-month window that surrounds your 65th birthday. Acting during this period is important — missing it can result in permanent late enrollment penalties and gaps in coverage.
When Does Your IEP Start?
Your Initial Enrollment Period spans 7 months total:
- 3 months before the month you turn 65
- The month you turn 65
- 3 months after the month you turn 65
Example: If your birthday is June 15, your IEP runs from March 1 through September 30.
When Coverage Begins Depends on When You Enroll
The timing of your enrollment within the IEP affects when your coverage starts:
| When You Enroll | Coverage Start Date |
|---|---|
| 1–3 months before your birthday month | The 1st of your birthday month |
| Your birthday month | The 1st of the following month |
| 1 month after your birthday month | 2 months after you enroll |
| 2–3 months after your birthday month | 3 months after you enroll |
Enrolling before your birthday month is generally the best strategy to ensure seamless coverage with no gap.
What to Enroll In During Your IEP
During your IEP, you can enroll in:
- Medicare Part A (Hospital Insurance) — free for most people
- Medicare Part B (Medical Insurance) — requires a monthly premium
- Medicare Part D (Prescription Drug Coverage) — offered through private plans
- Medicare Advantage (Part C) — as an alternative to Original Medicare
Do You Have to Enroll at 65?
Not always. You may be able to delay Part B (and Part D) without penalty if you have qualifying employer-sponsored health coverage through your own or a spouse's active employment. In that case, you'd use a Special Enrollment Period when that coverage ends.
However, if you do not have creditable coverage and miss your IEP, you'll face late enrollment penalties:
- Part B penalty: 10% added to your premium for each full 12-month period you could have enrolled but didn't — for as long as you have Part B.
- Part D penalty: 1% of the national base beneficiary premium per month you went without creditable drug coverage — added to your premium permanently.
How to Enroll in Medicare
There are three ways to sign up:
- Online: Visit ssa.gov to apply for Medicare Part A and/or Part B through the Social Security Administration.
- By phone: Call Social Security at 1-800-772-1213 (TTY: 1-800-325-0778).
- In person: Visit your local Social Security office.
If you're already receiving Social Security benefits when you turn 65, you'll typically be enrolled in Parts A and B automatically.
Special Note: Part A Only Enrollment
Many people choose to sign up for Part A only at 65 (since it's usually premium-free) while delaying Part B if they still have employer coverage. This is a common and acceptable strategy — just be sure to track your Special Enrollment Period for Part B when your employer coverage ends.
Key Takeaways
- Your IEP is a 7-month window around your 65th birthday.
- Enrolling early ensures timely coverage start.
- Missing the IEP without qualifying coverage triggers permanent penalties.
- Automatic enrollment applies if you're already on Social Security benefits.