Medicare Enrollment Periods & Deadlines
Key Takeaways
- Your Initial Enrollment Period (IEP) is the 7 months around your 65th birthday — don't miss it
- The Annual Enrollment Period (Oct 15 – Dec 7) is when most people make plan changes
- Missing deadlines can result in permanent late enrollment penalties
- Special Enrollment Periods exist for qualifying life events
Table of Contents
Medicare Enrollment at a Glance
Medicare has several enrollment windows throughout the year, each with different rules about who can enroll and what changes can be made. Understanding these periods — and their deadlines — is crucial to avoiding gaps in coverage and costly penalties.
Important: Enrollment Deadlines Are Strict
Unlike most insurance, Medicare late enrollment penalties are permanent — they're added to your premium for as long as you have Medicare. Planning ahead is essential.
All Enrollment Periods Explained
Initial Enrollment Period (IEP)
7-month window around your 65th birthday
Starts 3 months before your 65th birthday month, includes your birthday month, and ends 3 months after. This is the most critical enrollment window.
Who It's For
Everyone turning 65 who isn't auto-enrolled
What You Can Do
Sign up for Part A, Part B, Part D, or Medicare Advantage
Annual Enrollment Period (AEP)
October 15 – December 7 each year
The main annual window to make changes. Any changes take effect January 1 of the following year.
Who It's For
All Medicare beneficiaries
What You Can Do
Switch Advantage plans, add/drop Part D, switch between Original Medicare and Advantage
Medicare Advantage Open Enrollment (MA OEP)
January 1 – March 31 each year
A secondary window specifically for people already in Medicare Advantage plans. Changes take effect the first of the following month.
Who It's For
Current Medicare Advantage enrollees only
What You Can Do
Switch to a different Advantage plan, or drop Advantage and return to Original Medicare + Part D
General Enrollment Period (GEP)
January 1 – March 31 each year
For people who missed their IEP. Coverage starts July 1. Late enrollment penalties may apply permanently.
Who It's For
People who missed their IEP
What You Can Do
Sign up for Part A and/or Part B
Special Enrollment Period (SEP)
Varies by qualifying event
Triggered by specific life events. Duration varies — typically 2-8 months depending on the event.
Who It's For
People with qualifying life events
What You Can Do
Enroll in or change coverage outside regular enrollment periods
Special Enrollment Period Qualifying Events
Special Enrollment Periods (SEPs) allow you to make changes outside of regular enrollment windows. Common qualifying events include:
Late Enrollment Penalties
If you don't sign up for Medicare when you're first eligible and don't have qualifying coverage, you may face permanent premium penalties:
Part A Late Penalty
Penalty: 10% higher premium for twice the number of years you didn't enroll
Example: If you delayed 2 years, you'd pay the penalty for 4 years
Only applies if you don't qualify for premium-free Part A
Part B Late Penalty
Penalty: 10% surcharge for each full 12-month period you delayed
Example: 2 years late = 20% higher premium — permanently
This penalty lasts for as long as you have Part B
Part D Late Penalty
Penalty: 1% of the national base premium × number of months without coverage
Example: 12 months without coverage = ~$4/month added to your premium permanently
Applies if you go 63+ days without creditable drug coverage
Turning 65? Your Medicare Enrollment Checklist
12 months before turning 65
Start researching Medicare options. Understand Parts A, B, C, and D. Learn more →
3 months before turning 65
Your Initial Enrollment Period begins. Sign up for Part A and Part B if not auto-enrolled.
During your IEP
Decide between Original Medicare + Medigap + Part D vs. Medicare Advantage. Learn more →
Before your IEP ends
Complete all enrollments to avoid late penalties. Coverage starts the month you turn 65 (if enrolled early).
Each fall (Oct 15–Dec 7)
Review your plan during Annual Enrollment. Benefits, costs, and drug formularies change every year.
Not sure when to enroll or what to choose?
Talk to a licensed Medicare advisor — it's free and there's no obligation.
Disclaimer
We are not affiliated with Medicare or any government agency. This content is for informational purposes only. Calling the phone number on this page will connect you with a licensed insurance agent. Medicare has neither reviewed nor endorsed this information.
Got Questions?
Frequently Asked Questions
If you miss your IEP and don't qualify for a Special Enrollment Period, you'll have to wait for the General Enrollment Period (January 1 – March 31). Coverage won't start until July 1, and you may face a permanent 10% Part B late enrollment penalty for each full 12-month period you were eligible but didn't enroll.
Generally, no. However, Special Enrollment Periods (SEPs) allow changes if you experience qualifying life events like losing employer coverage, moving, qualifying for Medicaid, or entering/leaving a nursing home.
If you sign up during the first 3 months of your IEP, coverage starts the month you turn 65. If you sign up during your birthday month, coverage starts the following month. If you sign up in months 5-7 of your IEP, there will be a 1-3 month delay.
No, your Medicare coverage automatically renews. However, you should review your plan annually during the Annual Enrollment Period (Oct 15 – Dec 7) because plan benefits, costs, and drug formularies change each year.
The MA OEP runs January 1 – March 31 each year. If you're already enrolled in a Medicare Advantage plan, you can switch to a different Advantage plan or drop your Advantage plan and return to Original Medicare (and join a standalone Part D plan).
Don't Miss Your Medicare Enrollment Window
Check your eligibility in under 2 minutes — it's free, with no obligation