Medicare enrollment periods
| Period | When | What you can do |
|---|---|---|
| Initial Enrollment Period | 3 months before to 3 months after the month you turn 65 | First sign-up for Parts A and B (and D) |
| General Enrollment Period | January 1 – March 31 each year | Sign up if you missed your first window (penalties may apply) |
| Open Enrollment | October 15 – December 7 each year | Change Medicare Advantage or drug plans |
| Special Enrollment Period | Up to 8 months after work coverage ends | Sign up without penalty if you had job-based coverage |
Still working at 65?
If you (or your spouse) have health insurance from a current job at a company with 20 or more employees, you may be able to delay Part B without a penalty and sign up later during a Special Enrollment Period. Check with your employer’s benefits office first.
Frequently asked questions
When should I sign up for Medicare?
During your 7-month Initial Enrollment Period, ideally in the 3 months before your 65th birthday month so coverage starts right away.
Is Medicare automatic at 65?
Only if you’re already getting Social Security (or Railroad Retirement) benefits. Otherwise you need to sign up, usually at SSA.gov.
What happens if I miss my Medicare enrollment?
You can sign up during the General Enrollment Period (Jan 1–Mar 31), but you may pay a late penalty for as long as you have Part B.
What if my birthday is on the 1st of the month?
Medicare treats you as turning 65 in the previous month, so your whole window moves one month earlier.
Sources
- Medicare.gov – When does Medicare coverage start?
- Social Security Administration – Apply for Medicare
Last reviewed: November 2026 · By the GoldenYearsTools team at XplainedDaily · How we build our tools