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Medicare 101

When can I enroll? IEP, AEP, and SEP made simple

Posted June 15, 2026

Medicare runs on windows. Miss one and you can face a delay or a lasting penalty, so they’re worth knowing. There are three you’ll hear about.

IEP, your Initial Enrollment Period

This is your first window, built around your 65th birthday. It’s 7 months long: the 3 months before your birthday month, your birthday month, and the 3 months after.

This is when most people first sign up for Part A and Part B and choose their plan. Signing up in the first half of the window helps your coverage start without a gap.

AEP, the Annual Enrollment Period

Every year, from October 15 to December 7, anyone on Medicare can review and change their coverage for the following year. You can switch between Original Medicare and Medicare Advantage, change drug plans, and more. Changes take effect January 1.

Even if you’re happy, it’s worth a quick yearly check, because plans can change their costs and what they cover from one year to the next. The plan that fit this year isn’t automatically the best fit next year.

SEP, a Special Enrollment Period

Life doesn’t always line up with a calendar. A Special Enrollment Period is an extra window you get when something specific happens, such as:

  • You move out of your plan’s service area.
  • You lose other coverage, like a plan from an employer.
  • Certain other qualifying changes in your situation.

SEPs come with their own timing and rules, so if your life changes, it’s worth a quick call to see what window you have.

A quick word on penalties

If you skip Part B or Part D when you’re first eligible, and you don’t have other qualifying coverage, you can pay a late penalty that sticks with you for as long as you have the coverage. That’s the trap I most like to help people avoid, and it’s usually avoidable with a little planning.

Not sure which window you’re in? That’s an easy one to sort out together. Call or text me, no cost, no pressure. You can also confirm anything at Medicare.gov or 1-800-MEDICARE.

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