Medicare enrollment is not a single event but a series of specific windows throughout the year. For 2026, understanding these dates is vital to avoid permanent late-enrollment penalties and to ensure your coverage begins exactly when you need it.

Initial Enrollment Period (IEP)

This is your first opportunity to sign up for Medicare, centered around your 65th birthday.

  • The 7-Month Window: It includes the three months before your birthday month, the month you turn 65, and the three months after.
  • Effective Dates: If you sign up during the first three months, your coverage typically starts on the first day of your birthday month.
  • Penalty Protection: Enrolling during this window ensures you avoid the Part B and Part D late-enrollment penalties that can last for the rest of your life.

General Enrollment Period (GEP)

If you missed your Initial Enrollment Period and do not qualify for a special exception, you must use the GEP.

  • 2026 Dates: January 1 – March 31.
  • Coverage Start: Your coverage will begin the first day of the month after you sign up.
  • The Cost of Waiting: You may be required to pay a late-enrollment penalty, which adds an extra 10% to your Part B premium for every 12-month period you were eligible but not enrolled.

Annual Open Enrollment Period (AEP)

The AEP is the yearly “check-up” period for those already enrolled in Medicare.

  • 2026 Dates: October 15 – December 7.
  • What You Can Do: You can switch from Original Medicare to a Medicare Advantage plan, change from one Advantage plan to another, or switch your Part D prescription drug plan.
  • Final Result: Any changes you make during this window will take effect on January 1, 2027.

Medicare Advantage Open Enrollment Period (MA OEP)

This is a specific window only for individuals who are already enrolled in a Medicare Advantage plan.

  • 2026 Dates: January 1 – March 31.
  • The “One-Time” Change: During this period, you can switch to a different Medicare Advantage plan or drop your Advantage plan and return to Original Medicare.
  • New for 2026: A temporary Special Enrollment Period has been added for 2026 for enrollees who chose a plan based on inaccurate provider information in the Medicare Plan Finder tool.

Special Enrollment Periods (SEP)

Certain life events allow you to sign up for or change your Medicare coverage outside of the standard windows.

  • Working Past 65: If you have “creditable” health coverage through your own or your spouse’s current employer, you have an 8-month SEP to sign up for Part B once that employment or coverage ends.
  • Moving: If you move to a new address outside your plan’s service area, you typically have two months to switch to a new plan.
  • Other Events: Gaining or losing Medicaid eligibility, moving into a nursing home, or your plan leaving the Medicare program also trigger an SEP.

Source: Centers for Medicare & Medicaid Services (CMS), “Medicare & You 2026 Handbook”; and Social Security Administration (SSA) Fact Sheet, “2026 Enrollment Periods.”