Medicare Enrollment Periods Explained: When to Sign Up and When to Switch
Key takeaways
- Your Initial Enrollment Period is 7 months: the 3 months before the month you turn 65, that month, and the 3 months after.
- Annual Enrollment runs October 15 to December 7, with changes starting January 1.
- If you're in Medicare Advantage, you can make one change from January 1 to March 31.
- Your best time to buy a Medicare Supplement is the 6 months after you're 65 and enrolled in Part B.
Initial Enrollment Period
The 7-month window around your 65th birthday when you first sign up for Parts A and B. Enrolling in the 3 months before your birthday month helps your coverage start on time.
Annual Enrollment Period (October 15 to December 7)
Each fall you can switch between Original Medicare and Medicare Advantage, change Medicare Advantage plans, or join, switch or drop a Part D drug plan. Plans change their costs and drug lists every year, so it's worth a review.
Medicare Advantage Open Enrollment (January 1 to March 31)
If you're already in a Medicare Advantage plan, you can switch to a different one or go back to Original Medicare (and add a Part D plan) once during this window.
Medicare Supplement (Medigap) Open Enrollment
A one-time 6-month window that starts the first month you're both 65 or older and enrolled in Part B. During it, insurers generally can't deny you or charge more because of your health.
Still working at 65?
If you have coverage through your own or your spouse's current job, you may be able to delay Part B without a penalty and sign up later during a Special Enrollment Period. The rules depend on the employer's size, so check before you decide.
Frequently asked questions
What happens if I miss my Initial Enrollment Period?
You can sign up during the General Enrollment Period, January 1 to March 31, but you may pay a late enrollment penalty for as long as you have Part B.
Can I change my Medicare plan any time?
Generally only during the enrollment periods above, unless you qualify for a Special Enrollment Period, such as after a move.
Does a Medicare agent cost anything?
No. Plan premiums are the same whether you enroll on your own or with an agent.
This guide is general information, not tax or legal advice. Rules and dates can change each year; confirm details for your state with your agent or the official source.