Medicare Annual Enrollment: The 5 Deadlines That Matter

1. Annual Enrollment: October 15 to December 7

This is the main yearly window for changing Medicare Advantage and Part D coverage for the following year. Changes submitted by December 7 generally take effect January 1.

2. Medicare Advantage Open Enrollment: January 1 to March 31

If you are already enrolled in Medicare Advantage, you can generally make one change during this period: switch to another Medicare Advantage plan or return to Original Medicare and add Part D.

3. Your Initial Enrollment Period

For most people first eligible at 65, the Initial Enrollment Period spans seven months around the 65th birthday month. Employer coverage and disability-based Medicare can change the timing.

4. Special Enrollment Periods

A move, loss of other coverage, certain Medicaid or Extra Help changes, or other qualifying events can trigger a Special Enrollment Period. The action allowed and deadline depend on the specific event.

5. The 63-day Part D creditable coverage rule

Going 63 days or more in a row without Medicare drug coverage or other creditable prescription coverage can lead to a Part D late enrollment penalty when you later enroll.

2027 Part D numbers to know

For 2027, the defined standard Part D deductible is $700 and the annual out-of-pocket threshold is $2,400. These are federal benefit parameters; each plan can still differ in premiums, formulary structure, preferred pharmacies and other cost sharing.

Your AEP review checklist

• Read your Annual Notice of Change.
• Confirm doctors, specialists and hospitals.
• Check every prescription and preferred pharmacy.
• Compare total annual costs, not just the premium.
• Review supplemental benefits only when they are documented for the exact plan and eligibility.