What it is: Your first main chance to sign up for Medicare Part A and Part B. It’s the window most people use when they’re first becoming eligible.

Who it’s for: People turning 65 (or otherwise first becoming eligible for Medicare).

When it happens: A 7-month window: three months before your 65th birthday month, your birthday month, and three months after.

What you can do:

• Enroll in Part A and/or Part B.

• Set yourself up to choose a Part D drug plan or Medicare Advantage plan (Part C), if you want additional coverage.

Big watch-out: If you miss your IEP and don’t qualify for a Special Enrollment Period, you may have to wait for the General Enrollment Period and could face late enrollment penalties. If you’re still working and have employer coverage, make sure you understand the “working past 65” rules before delaying Part B.